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North Marin Water District

Maintenance Department - Frequently Asked Questions


All of the NMWD facility maintenance is performed by its Maintenance Department, except for office janitorial services. This includes maintenance at 42 tanks, 32 pump stations, 7 hydro pneumatic systems and 13 regulating stations and 2 water treatment plants.  The Maintenance Department is divided into two sections to achieve optimum efficiency.

The Transmission and Distribution (T&D) section is responsible for maintenance of  water distribution equipment and facilities including valves, hydrants, cross-connection prevention devices, fire detector check assemblies, and some meter maintenance. The same section is responsible for customer service leaks and repairs, fire flow testing, system flushing and minor construction and repair works. Every year, this section tests and repairs approximately 2,300 fire hydrants and about 3,500 valves. Also, T&D tests over 1,000 back flow, or cross-connection, devices and repairs or replaces those that are malfunctioning. Additionally, over 300 fire detector/check assemblies are tested annually and repaired if necessary.

The Electro/Mechanical (E/M) section is responsible for operation and maintenance of all E/M systems, including motors, pumps, instrumentation and controls, telemetry, electrical power distribution, emergency generators, indoor/outdoor lighting, cathodic protection, regulating stations and hydro pneumatic tanks. This section also supports Operations and provides maintenance services for the Distribution Control and Monitoring System, and facilitates repair and installation of radios, telephones and other communication equipment and systems.

A cross connection is a condition that exists when a potable water pipe is connected to a non-potable pipe or another source of water (such as a private well).  A cross connection is dangerous because the connection makes it possible for non-potable and sometimes hazardous liquids to flow into the potable supply.  Under unusual pressure circumstances, it is possible that contaminated water could backflow through the water meter and contaminate the NMWD supply.

California health regulations require that property owners, who have the possibility of a cross connection occurring on their property, prevent any potential backflow by installing a backflow prevention device, either a "double-check valve" or a "reduced-pressure principle assembly."

Yes, in most cases, because of State laws and NMWD Regulations.
NMWD doesn't require each irrigation system to have a backflow device because the water used for your irrigation system is the same water that you use for cooking, drinking, washing and bathing However, you do need properly-installed backflow protection.
Residential fire sprinklers systems are typically separated by a one-way check valve located above the house shut-off valve.
Yes, if the make-up supply line to the pool/tub is plumbed under the fill rim, without an anti-siphon device.
Yes and no. If your solar heating system is a “once through” type, there is no problem. However, if your system is looped and uses corrosive inhibitors, antifreeze, or single walled heat exchangers, you will need backflow protection.
Yes. If the water plumbed out over or under your dock is used for wash down or to raise your boat out of the lagoon, you need to install a backflow prevention device.
Pressure regulators are used to lower water pressure to your house in areas where the NMWD main water pressure is high. 
Water is taken from the lower elevations and pumped up to storage tanks situated in the hills around Novato. There are controls that keep the tanks full, turn off the pumps when necessary and prevent the tanks from overflowing.