Cambridge Water Department

Cambridge's reservoir system water undergoes comprehensive treatment at the Walter J. Sullivan Water Purification Facility in Fresh Fish Pond Reservation before delivery to homes and businesses. The water is processed to exceed all state and federal standards through a multi-step approach:

1. Pretreatment: Initial processes combine peroxidation with ozone, coagulation, and dissolved air flotation (DAF) to eliminate manganese, organic materials, sediment, algae, harmful microorganisms, viruses, and bacteria.

2. Ozone Treatment: Ozone bubbles are dissolved into water to destroy bacteria, viruses, and protozoa effectively.

3. Filtration: Water passes through granular activated carbon (GAC) to remove organic compounds. This filtration also acts as a polishing step to eliminate additional contaminants and color.

4. Disinfection: Chlorine provides a secondary disinfection stage for redundancy, while monochloramine maintains disinfectant levels throughout the distribution network.

5. Final Adjustments: pH is balanced for corrosion control and fluoride is added for dental health benefits.

The Cambridge Water Department's laboratory continuously monitors treatment effectiveness and makes adjustments to ensure optimal water quality. Residents can tour the treatment facility led by Timothy MacDonald, Director of Water Operations. Tours are scheduled monthly and last approximately 30 minutes.

Reservoir System:
The Cambridge Water System spans four municipalities and includes four water bodies. Hobbs Brook Upper Reservoir flows to the Lower Reservoir, connecting with Stony Brook Reservoir. Water then travels to Fresh Pond Reservoir via underground aqueduct. The watershed extends across Weston, Lincoln, Waltham, and Lexington, with the Fresh Pond Reservoir watershed entirely within Cambridge. The combined capacity of the reservoir system exceeds 4.4 billion gallons, with additional support from Massachusetts Water Resources Authority (MWRA) interconnections.

Watershed Protection:
Cambridge Water Department collaborates with MassDEP on the Source Water Assessment Program (SWAP) to protect public water supplies. Due to developed land uses within the Cambridge watershed, source waters are rated as having "high" susceptibility to contamination. The department has implemented multiple protective measures including emergency response coordination, stormwater management, strategic spill kit placement, continuous water quality monitoring, business cooperation, and comprehensive protection planning.

1. Why does my water appear milky or cloudy?
   This cloudiness is simply trapped air in the water, which is completely safe to drink. It's most noticeable when water temperature is cooler than room temperature. The effect may be enhanced by aerators on faucets. No action is needed as this is not harmful.
2. Why does my water look brown or orange after periods of non-use?
   This is typically caused by rust in your home's internal plumbing. Running the water for several minutes until it clears should resolve the issue.
3. Why is my entire neighborhood experiencing discolored water?
   Contact Cambridge Water at 617-349-4770. This often occurs when nearby hydrants are in use or construction activity creates vibrations that disturb mineral deposits in water mains. Running cold water from taps closest to your water meter can help clear the system faster.
4. What causes the black ring in my toilet bowl?
   This is mold growth related to room temperature, usage patterns, and ventilation - not water quality. A chlorine-based cleaner and improved airflow during showers can help prevent this.
5. What are the particles clogging my fixtures?
   Test by placing particles in vinegar. If they dissolve, they're likely mineral deposits, which are natural. If they don't dissolve, they may be plastic fragments from a deteriorating water heater "dip tube," which might require replacement.
6. Can tap water cause skin rashes?
   Water typically doesn't cause skin conditions but may aggravate existing ones like eczema or dry skin. Rather than hydrating, water may sometimes draw moisture from skin. Consult your healthcare provider for appropriate treatments.
7. Why does my water taste and smell earthy at certain times?
   During late summer through fall, you might notice taste and odor issues due to algae in source waters. While filtration removes algae, some taste compounds may remain. Despite the flavor, the water remains safe to drink. Chilling water in your refrigerator can reduce these taste effects.
8. Why did my aquarium fish die after adding fresh tap water?
   Tap water contains chlorine disinfectants that are lethal to fish. Always use a dechlorination product (available at pet stores) or let water stand in an open container to allow chlorine to dissipate naturally before adding to aquariums.