Best Water Softener for Tulsa, OK — 17 Things to Know BEFORE You Buy!

Written by Craig "The Water Guy" Phillips

1. The Local Water Problem in Tulsa, OK

Walk into any Tulsa appliance repair shop, and you'll hear the same story repeated dozens of times each week: "My water heater is only three years old, but it's already failing." The culprit isn't poor manufacturing or bad luck — it's Tulsa's 8.5 grains per gallon (GPG) water hardness systematically destroying home infrastructure across the metro area.

To understand what 8.5 GPG means, imagine your water as a liquid carrying dissolved limestone particles through every pipe, faucet, and appliance in your home. Each gallon of Tulsa water contains 8.5 grains worth of calcium and magnesium minerals — enough dissolved rock to coat heating elements, narrow pipes, and turn your expensive appliances into expensive paperweights.

Tulsa draws its water primarily from Oologah Lake and the Arkansas River, both of which flow through limestone-rich geology that naturally dissolves calcium and magnesium into the water supply. At 8.5 GPG, Tulsa's water is classified as "hard" — a designation that translates into measurable damage for every home in the city. This isn't the slightly elevated mineral content you might find in suburban communities; this is water hard enough to cut appliance lifespans by 30-50% and triple your soap and energy costs.

The financial stakes for Tulsa homeowners are immediate and compounding. A typical Tulsa household loses approximately $1,200-1,800 annually to hard water damage — through premature appliance replacement, doubled energy bills, and the constant purchase of extra soap and detergent that gets wasted fighting mineral buildup. When you factor in the reduced home value from scale-damaged fixtures and the ongoing frustration of dealing with spotty dishes, stiff laundry, and soap scum that seems to regenerate overnight, the true cost becomes clear: Tulsa's hard water isn't just an inconvenience — it's a tax on every aspect of home ownership.

2. What 8.5 GPG Does to Your Home

At 8.5 GPG, calcium carbonate doesn't just coat your water heater's heating elements — it forms thick, insulating layers that force the system to work 25-35% harder to heat the same amount of water. Inside a typical Tulsa home's 40-gallon water heater, mineral deposits accumulate at a rate of roughly 2-3 pounds per year. These limestone-like formations act as thermal insulators, preventing efficient heat transfer and causing energy bills to climb month after month.

The crystallization process happens every time Tulsa's mineral-rich water is heated or evaporates. Calcium and magnesium ions bond directly to metal surfaces, forming calcite crystals that grow thicker with each heating cycle. A water heater that should last 10-12 years in a soft-water city will typically fail in 6-8 years in Tulsa, not from normal wear but from scale-induced overheating and element burnout.

Tulsa's older neighborhoods, particularly those with galvanized steel plumbing installed before 1980, face an accelerated timeline for pipe replacement. At 8.5 GPG, galvanized pipes develop measurable diameter reduction within 8-10 years, compared to 15-20 years in soft-water areas. The minerals form concentric rings inside the pipe walls, gradually choking off water flow and creating pressure drops that affect shower performance and appliance operation.

Your major appliances bear the brunt of Tulsa's mineral assault daily. Dishwashers in 8.5 GPG water typically require replacement every 7-8 years instead of the expected 10-12 years, while washing machines lose efficiency within 5-6 years as mineral buildup clogs spray arms, pumps, and internal components. Tankless water heaters, increasingly popular in new Tulsa construction, are particularly vulnerable — many manufacturers void warranties if the units aren't protected by a water softener in areas exceeding 7 GPG.

The soap and detergent waste in Tulsa homes is both measurable and expensive. At 8.5 GPG, calcium and magnesium ions chemically react with soap molecules to form insoluble curds instead of producing cleaning lather. This means Tulsa residents typically use 3-4 times more laundry detergent, dish soap, and shampoo compared to soft-water areas. For an average household, this translates to an extra $300-400 annually spent on cleaning products that are largely wasted fighting mineral interference.

The impact on skin and hair becomes noticeable within weeks of moving to Tulsa. Calcium ions strip natural oils from skin and coat hair shafts, leaving residents with dry, itchy skin and dull, lifeless hair that feels rough to the touch. Dermatologists in the Tulsa area report higher rates of eczema and skin sensitivity complaints, particularly among children and adults with already-sensitive skin conditions.

Laundry emerges from Tulsa washing machines bearing the mineral signature of 8.5 GPG water. Fabrics become gray, stiff, and scratchy as calcium deposits embed in cloth fibers, while white clothing develops a dingy appearance that no amount of bleach can restore. The minerals also interact with fabric dyes, causing colors to fade faster and making new clothing look prematurely aged after just a few wash cycles.

Adding up the energy waste, appliance depreciation, extra soap costs, and premature replacement schedules, a typical Tulsa household pays an estimated $1,400-1,700 annually in direct hard water costs — what amounts to a monthly "mineral tax" of $115-140 that most homeowners never realize they're paying.

3. Tulsa's Specific Contaminant Profile

Beyond the baseline challenge of 8.5 GPG hardness, Tulsa residents are also contending with chloramine, iron, and sediment — each of which interacts with water hardness in its own problematic way. Understanding how these contaminants behave in Tulsa's mineral-rich environment is essential for choosing the right treatment approach.

Chloramine in Tulsa's Water Supply

Tulsa Water uses chloramine as its primary disinfectant — a combination of chlorine and ammonia that's more stable than chlorine alone but significantly harder to remove from drinking water. The city switched to chloramine treatment to meet federal disinfection byproduct regulations, but the change created new challenges for Tulsa homeowners. Chloramine enters Tulsa's water at the treatment plants and remains active throughout the distribution system, including inside your home's plumbing.

At 8.5 GPG hardness, chloramine becomes more problematic because the mineral-rich environment can catalyze reactions between chloramine and metal pipes, particularly in older Tulsa neighborhoods with copper or galvanized steel plumbing. Residents typically notice chloramine through a distinctive "band-aid" or medicinal odor, especially when running hot water for showers or dishwashing. The smell intensifies in summer months when water temperatures are higher and chloramine is more volatile.

Tulsa's chloramine levels typically range between 1.5-3.0 mg/L, well within EPA guidelines but high enough to cause taste and odor issues. Standard water softeners do NOT remove chloramine — addressing this contaminant requires a separate catalytic carbon filter specifically designed for chloramine reduction. For Tulsa residents dealing with both hardness and chloramine, a two-stage treatment approach is necessary.

Iron in Tulsa's Water

Iron enters Tulsa's water supply through natural geological processes as groundwater interacts with iron-bearing minerals in the Arkansas River basin. Most Tulsa residents encounter ferrous iron — the dissolved, invisible form that only becomes problematic when it oxidizes upon contact with air or when heated.

The interaction between iron and Tulsa's 8.5 GPG hardness creates compounded staining problems throughout the home. Iron bonds with calcium deposits, creating orange-brown stains on toilets, bathtubs, and appliance interiors that become increasingly difficult to remove over time. In dishwashers, the combination of iron, calcium, and heat produces permanent staining on the interior walls and door seals.

Tulsa's iron levels typically measure 0.2-0.8 mg/L, with seasonal variation depending on rainfall and river conditions. While this is generally below the EPA's secondary maximum contaminant level of 0.3 mg/L, iron above 0.2 mg/L can foul water softener resin when combined with 8.5 GPG hardness. For Tulsa homes with detectable iron, an iron pre-filter upstream of the water softener prevents resin damage and extends system life.

Sediment in Tulsa's Distribution System

Sediment in Tulsa's water comes primarily from aging distribution pipes and periodic main breaks rather than source water contamination. The city's water infrastructure includes pipes installed over several decades, and older cast iron and steel mains naturally contribute particulate matter as they corrode and scale internally.

Sediment becomes more problematic in Tulsa's 8.5 GPG environment because suspended particles provide nucleation sites for calcium and magnesium precipitation. This means sediment and hardness minerals tend to bind together, creating larger particles that can clog appliance screens, faucet aerators, and water softener components more quickly than in soft-water cities.

Tulsa residents typically notice sediment as occasional cloudiness in cold water or small particles that settle in glasses of water left standing. While sediment levels are generally low and meet all EPA turbidity standards, protecting water softener resin from particulate damage is important for system longevity at 8.5 GPG usage rates. The SoftPro Elite HE's built-in sediment pre-filter addresses this specific challenge for Tulsa installations.

4. Why Most Tulsa Homeowners Pick the Wrong Softener

After reviewing dozens of failed water softener installations across Tulsa, four mistakes appear repeatedly — mistakes that turn what should be a 10-15 year investment into a frustrating cycle of repairs and replacements. Here's what I wish someone had told these homeowners before they bought the wrong system.

The first and most costly mistake is buying on price alone. A 24,000-grain softener that might adequately serve a household in Oklahoma City or Kansas City will be completely overwhelmed by continuous 8.5 GPG demand in Tulsa. Resin exhaustion happens faster at higher GPG levels, meaning an undersized unit regenerates constantly, wastes salt, and still allows periodic hard water breakthrough. Several Tulsa homeowners reported their "bargain" softeners failing within 18-24 months because the units simply couldn't keep up with the mineral load.

The second mistake is confusing water softeners with water filters. Softeners use ion exchange to remove calcium and magnesium — period. They do NOT reliably remove chloramine, iron, or sediment from Tulsa's water supply. Tulsa residents dealing with both 8.5 GPG hardness and taste/odor issues need a two-stage approach: softening for mineral removal and separate filtration for contaminants. Expecting one system to solve all problems leads to disappointment and continued water quality issues.

The third mistake involves ignoring basic grain capacity mathematics. The sizing formula is straightforward: household members × 75 gallons per day × 8.5 GPG = daily grain demand. For a family of four in Tulsa, that's 4 × 75 × 8.5 = 2,550 grains consumed daily. Multiply by seven days, add a 20% buffer for high-usage periods, and you need approximately 21,400 grains of weekly capacity. This means a 32,000-grain system operating with regeneration every 5-7 days — optimal for efficiency and performance.

The fourth mistake is overlooking salt efficiency ratings, which become critical at 8.5 GPG consumption levels. An inefficient softener might use 12-15 pounds of salt per regeneration, while a high-efficiency model uses 6-8 pounds for the same grain capacity. Over 10 years in Tulsa, this difference compounds to 3,000-4,000 extra pounds of salt — representing $800-1,200 in unnecessary operating costs plus the ongoing hassle of more frequent salt deliveries or store trips.

5. The SoftPro Elite HE: Built for Tulsa's Water

After evaluating Tulsa's water hardness of 8.5 GPG and the presence of chloramine, iron, and sediment in the local supply, one system consistently rises to the top for Tulsa homeowners: the SoftPro Elite HE Water Softener. This isn't marketing convenience — it's the logical conclusion when matching system capabilities to Tulsa's specific water chemistry challenges.

Salt-Based Ion Exchange for Real Hardness Removal

Salt-free "conditioners" do not actually remove hardness minerals — they only attempt to change crystal structure, a process that fails completely at 8.5 GPG levels. The SoftPro Elite HE uses true cation exchange resin to physically replace calcium and magnesium ions with sodium ions. This is the only treatment method that delivers genuinely soft water (under 1 GPG) when starting with Tulsa's 8.5 GPG baseline. For Tulsa residents tired of scale buildup and appliance damage, ion exchange isn't just preferred — it's the only technology that actually works.

Demand-Initiated Regeneration (DIR) Technology

At 8.5 GPG, water softener resin exhausts faster than in soft-water cities, making regeneration timing critical for consistent performance. The SoftPro's DIR system monitors actual water usage and resin capacity, regenerating only when the resin bed is actually depleted. This prevents hard water breakthrough (which happens when regeneration is delayed) and eliminates salt and water waste from unnecessary regeneration cycles. For Tulsa households consuming 2,500+ grains daily, DIR technology is operationally essential, not just convenient.

NSF/ANSI Standard 44 Certified Resin

Certification verifies that the resin meets strict performance and materials safety standards under continuous high-hardness operation. For Tulsa residents already managing chloramine, iron, and sediment in their water supply, knowing the softening process itself doesn't introduce additional contaminants is critical. The NSF certification provides third-party verification of both effectiveness and safety — particularly important for households with infants, elderly residents, or individuals with compromised immune systems.

Multiple Grain Capacity Options (32K, 48K, 64K, 80K)

Tulsa households need different capacity levels depending on family size and usage patterns. For a typical 4-person Tulsa household at 8.5 GPG, the calculation works out to: 4 people × 75 gallons daily × 8.5 GPG = 2,550 grains consumed daily, or 17,850 grains weekly. Adding a 20% buffer for high-usage periods brings the requirement to approximately 21,400 grains weekly. The SoftPro's 32,000-grain model handles this demand with regeneration every 5-6 days — the optimal frequency for salt efficiency and performance reliability.

10-Year Comprehensive Warranty

At 8.5 GPG hardness levels, water softener resin sees heavy daily use that would be considered extreme conditions in soft-water cities. The SoftPro's 10-year warranty covers both parts and performance, providing Tulsa homeowners with protection during the years when hardness-related stress on system components is highest. This warranty coverage reflects the manufacturer's confidence in the system's ability to handle demanding water conditions over the long term.

Compatibility with Pre-Filtration Systems

The SoftPro Elite HE is specifically designed to work downstream of iron and sediment filtration systems — crucial for Tulsa installations where these contaminants are present alongside 8.5 GPG hardness. Many softeners suffer resin fouling or mechanical damage when exposed to iron or particulate matter, but the SoftPro's design anticipates and accommodates pre-treatment. This compatibility eliminates the guesswork and potential warranty issues that arise when trying to integrate incompatible systems.

Built-In Sediment Pre-Filter

Before hardness minerals reach the main resin tank, the SoftPro's integrated sediment filter captures particulate matter that would otherwise accumulate in the resin bed. For Tulsa installations where both sediment and 8.5 GPG hardness are present simultaneously, this pre-filtration protects the expensive resin from premature fouling while maintaining optimal ion exchange efficiency. The filter is self-cleaning during regeneration cycles, requiring minimal maintenance while providing maximum protection.

For Tulsa households dealing with 8.5 GPG of water hardness and the compounding presence of chloramine, iron, and sediment, the SoftPro Elite HE is not a comfort upgrade — it is infrastructure protection for your home.

6. How to Size Your Softener for Tulsa

Proper sizing for Tulsa's 8.5 GPG water requires precise calculation — undersizing means constant regeneration and hard water breakthrough, while oversizing wastes money and salt. Follow this step-by-step process to determine the right SoftPro Elite HE model for your household.

Step 1: Count household members (include all full-time residents)

Step 2: Multiply by 75 gallons per person per day (standard consumption estimate)

Step 3: Multiply household gallons × 8.5 GPG = daily grain demand

Step 4: Multiply daily grains × 7 = weekly grain demand

Step 5: Add 20% buffer for high-usage days (laundry, guests, irrigation)

Step 6: Match result to SoftPro Elite HE grain capacity (32K / 48K / 64K / 80K)

Here's the calculation worked out for a 4-person Tulsa household:

4 people × 75 gallons = 300 gallons daily
300 gallons × 8.5 GPG = 2,550 grains daily
2,550 grains × 7 days = 17,850 grains weekly
17,850 + 20% buffer = 21,420 grains needed weekly

This household should choose the SoftPro Elite HE 32,000-grain model, which provides adequate capacity with regeneration every 5-6 days. Regenerating every 5-7 days optimizes salt efficiency while ensuring consistent soft water delivery. More frequent regeneration wastes salt and water, while less frequent regeneration risks resin exhaustion and hard water breakthrough during peak usage periods.

For larger Tulsa households (5-6 people), the 48,000-grain model handles the increased demand while maintaining the optimal regeneration schedule. Remember that Tulsa's 8.5 GPG hardness means your system works significantly harder than softeners in cities with 3-5 GPG water — proper sizing isn't just about convenience, it's about protecting your investment.

7. Installation in Tulsa: What to Know

Tulsa does not require a licensed plumber for water softener installation, but the complexity of integrating with pre-filtration systems for chloramine and iron often makes professional installation worthwhile. Most experienced Tulsa installers are familiar with the city's water challenges and can ensure proper system placement and configuration.

The optimal placement sequence for Tulsa homes is: main water shutoff valve → sediment pre-filter (if needed) → iron filter (if needed) → water softener → water heater and household distribution. This arrangement ensures that contaminants are removed before reaching the softener resin, while softened water protects all downstream appliances and fixtures. The softener must be positioned after the main shutoff but before the water heater to treat all hot water usage.

Plan for a drain line connection within 20 feet of the installation location. The SoftPro Elite HE requires gravity drainage or a drain pump for regeneration discharge — typically 40-60 gallons every 5-7 days at Tulsa's 8.5 GPG consumption rate. The drain line can connect to a utility sink, floor drain, or (with local code approval) directly to the sewer line.

Tulsa's municipal water pressure typically ranges from 45-65 PSI, which is well within the SoftPro Elite HE's operating specifications. However, homes in elevated areas of South Tulsa or older neighborhoods with galvanized plumbing may experience lower pressure. If your home's water pressure is below 40 PSI, consider a pressure booster pump installation alongside the softener.

For salt selection at 8.5 GPG hardness, use high-purity evaporated pellets exclusively. Solar crystals and rock salt contain impurities that accumulate in the brine tank more quickly at higher regeneration frequencies, leading to bridging and system inefficiency. Evaporated pellets cost slightly more upfront but prevent maintenance headaches and ensure consistent performance in Tulsa's demanding water conditions.

Check salt levels monthly during the first year to establish your household's consumption pattern. At 8.5 GPG with a 32,000-grain system regenerating every 6 days, expect to use approximately 40-50 pounds of salt monthly for a 4-person household. Keep the brine tank at least 1/3 full, but don't overfill — excess salt can cause bridging and interfere with proper regeneration.

8. Maintenance Schedule for Tulsa Homeowners

Tulsa's 8.5 GPG hardness accelerates normal wear on water softener components, making proactive maintenance essential for long-term reliability. This schedule is calibrated specifically for Tulsa's water conditions and usage rates.

Monthly Tasks

Check salt level in the brine tank — consumption is moderate to high at 8.5 GPG, requiring monthly monitoring to prevent salt-out conditions. Look for salt bridges, which appear as a hard crust above the water line that prevents proper brine formation. Gently probe the salt with a broomstick to break up any bridging. Confirm the bypass valve remains in the "service" position unless you're performing maintenance.

Every 3 Months

Clean the brine tank to remove accumulated sediment and salt residue that builds up faster in high-hardness environments. Test post-softener water hardness with a test strip — readings should consistently show under 1 GPG. If hardness creeps above 1 GPG, investigate resin fouling, salt bridging, or regeneration timing issues. For Tulsa homes with iron present, inspect and clean the sediment pre-filter to maintain optimal flow rates.

Annual Maintenance

Perform comprehensive brine tank cleaning with complete water and salt removal. Check resin bed performance by testing hardness at multiple taps throughout the house. Iron-bearing water in Tulsa can cause orange staining on resin beads — use an iron-specific resin cleaner annually to maintain ion exchange capacity. Audit regeneration cycle timing and salt dosage to ensure efficiency remains optimal as the system ages.

Every 5 Years

Evaluate resin replacement needs — at 8.5 GPG, resin degrades faster than in soft-water cities due to higher mineral throughput and more frequent regeneration cycles. Professional resin testing can determine remaining capacity and help plan replacement timing. Consider upgrading control valve programming if newer efficiency algorithms become available.

Tulsa residents should establish baseline water hardness readings before installation and retest 30 days later to confirm the system is performing as expected. Keep regeneration frequency logs during the first year to identify seasonal usage patterns and optimize the system's programming for your household's specific needs.

9. Frequently Asked Questions for Tulsa Residents

9. Is Tulsa's water at 8.5 GPG dangerous to drink?

Tulsa's 8.5 GPG hardness is not dangerous to drink and actually provides beneficial calcium and magnesium minerals. The EPA does not regulate water hardness as a health concern. However, the high mineral content causes significant property damage, increased utility costs, and aesthetic issues like poor soap performance and skin dryness. Water softening is about protecting your home's infrastructure and improving quality of life, not addressing safety concerns.

10. Will a water softener remove chloramine from Tulsa's water?

No, water softeners do NOT remove chloramine from Tulsa's water supply. Softeners only remove hardness minerals (calcium and magnesium) through ion exchange. Chloramine requires a separate catalytic carbon filter specifically designed for chloramine reduction. For Tulsa residents concerned about both hardness and chloramine taste/odor, install a catalytic carbon whole-house filter before the water softener, or add a point-of-use carbon filter at drinking water taps.

11. How much salt will I use per month in Tulsa at 8.5 GPG?

A typical 4-person Tulsa household with a properly sized 32,000-grain softener will use approximately 40-50 pounds of salt monthly. This assumes regeneration every 5-6 days with the SoftPro Elite HE's efficient salt dosage. Larger households or higher-capacity systems will use proportionally more salt. At current salt prices, budget $15-25 monthly for salt costs, significantly less than the $115-140 monthly cost of living with untreated 8.5 GPG hard water.

12. Does Tulsa require a permit to install a water softener?

The City of Tulsa does not require permits for water softener installation in single-family homes. However, if the installation involves new plumbing connections or electrical work beyond simple plug-in operation, those modifications may require separate permits. Check with Tulsa's Development Services if your installation includes significant plumbing changes. Most residential softener installations are considered maintenance and improvement work that doesn't require city approval.

13. Why does soft water feel slippery in the shower?

Soft water feels slippery because you're experiencing clean skin for the first time without calcium ion interference. In Tulsa's 8.5 GPG hard water, calcium ions prevent soap from rinsing completely and strip natural oils from your skin. Soft water allows soap to lather properly and rinse cleanly, while your skin retains its natural moisture and oils. The "slippery" sensation is actually your skin's natural texture without mineral coating — most Tulsa residents prefer this feeling once they adjust.

14. How quickly will I see results after installing a softener in Tulsa?

Tulsa homeowners typically notice immediate improvements in soap lathering and reduced spotting on dishes within 24-48 hours of installation. Existing scale buildup on fixtures and appliances will gradually diminish over 2-3 months as soft water slowly dissolves accumulated deposits. Water heater efficiency improvements become measurable within 30-60 days as scale stops accumulating on heating elements. Skin and hair improvements are usually noticeable within the first week of showering with softened water.

15. Can the SoftPro Elite HE handle Tulsa's water without a separate filter?

The SoftPro Elite HE will effectively soften Tulsa's 8.5 GPG hardness and handle typical levels of iron and sediment with its built-in pre-filter. However, it does not remove chloramine, which requires a separate catalytic carbon filter for taste and odor improvement. For comprehensive treatment of Tulsa's water profile, most homeowners benefit from pairing the SoftPro with a catalytic carbon pre-filter to address chloramine while the softener handles hardness, iron, and sediment.

16. Final Verdict for Tulsa

Tulsa's hardness of 8.5 GPG demands professional-grade treatment — this isn't a minor water quality issue that can be addressed with basic filtration or ignored indefinitely. The combination of significant mineral content with chloramine disinfection creates a water profile that systematically damages appliances, wastes money, and degrades daily quality of life for residents throughout the metro area.

Chloramine, iron, and sediment compound the hardness problem by accelerating corrosion, creating additional staining, and introducing taste and odor issues that affect drinking water quality. These multiple contaminants require a thoughtful treatment approach that addresses each challenge appropriately rather than hoping one system can solve all problems.

The SoftPro Elite HE is the right match for Tulsa because its demand-initiated regeneration handles high mineral throughput efficiently, its NSF-certified resin maintains performance under continuous hard water stress, and its compatibility with pre-filtration systems allows for comprehensive water treatment. The 10-year warranty provides confidence for the long-term investment, while multiple grain capacity options ensure proper sizing for households of all sizes.

For Tulsa residents tired of replacing water heaters every 6 years, scrubbing mineral stains from fixtures, and dealing with dry skin and stiff laundry, the time for action is now. Check current SoftPro Elite HE pricing and available grain capacities for a Tulsa household — every month of delay means continued damage to your home's infrastructure and hundreds of dollars in wasted utility and soap costs.

The investment in proper water treatment pays for itself through extended appliance life, reduced energy bills, and elimination of the ongoing "hard water tax" that most Tulsa homeowners don't realize they're paying. Just like the oil derricks that built this city required the right equipment for the job, protecting your home from Tulsa's challenging water conditions requires the right system — and that system is the SoftPro Elite HE.

17. What to Do Next

Start by testing your current water to establish baseline hardness and iron levels — most Tulsa residents are surprised by how high their numbers actually test. Contact a local water treatment professional familiar with Tulsa's specific water challenges to evaluate your home's plumbing configuration and determine the optimal installation approach.

Calculate your household's grain capacity needs using the sizing formula provided, and request a detailed quote for the appropriate SoftPro Elite HE model plus any necessary pre-filtration for chloramine or iron. Don't wait until your next appliance fails or water heater replacement is needed — proactive installation saves thousands in avoided damage and operates more cost-effectively than reactive repairs.