At the service line connection with each customer, the water utility is required to install and maintain infrastructure that supports the meter placement including a yoke to hold the meter, backflow prevention device, a pressure relief valve (PRV), and/or other equipment (e.g., low flow batch device). These pieces of equipment wear out, and/or require upgrades or replacement as the meter ages, the connection changes hands or purpose, etc. Since some, if not all of the equipment is the responsibility of the utility, it is of benefit for the utility to track its age, location and costs for replacement. If some of the equipment is the responsibility of the customer (many utilities do not include PRVs as part of the provided utility equipment), it is still of benefit for the utility to track the location and age of these items.
Meter yokes are designed to speed meter installation and removal, and to absorb service line stresses which occur as temperature changes and distribution system conditions change. Yokes are specified based on the size of the meter, the diameter of the service lines (both coming from the utility and going to the customer), and the materials of the service lines. In addition, the meter yoke may be wide enough to allow for the installation of a batching device that can be used to capture low flows (less than .1 gpm).
Most water meters don’t measure low flow rates (less than 0.05 gallons per minute, which is 75 gallons per day). One potential solution, the UFR (Unmeasured-Flow Reducer), is a mechanical device that is installed in the service line immediately adjacent to the customer meter. Its main objective is to reduce the apparent losses by changing the flow regime through the water meter at low flow rates. This reduces the volume of unmeasured water at low flow rates and enables the measurement of slow leaks on the customer side (e.g., toilet leak, sink leak) by a domestic water meter. The cost of these devices can range from $50 to $200.
The UFR works by changing the way water flows through the meter at low flow rates. At low flow rates there is not enough energy in the flow to activate the water meter. With the UFR installed, the low, linear flows are divided into batches that are forced through the meter at a higher flow rate. These higher flows can now be registered by the water meter, reducing apparent losses and increasing revenue.
At normal household flow rates, the UFR is fully open, allowing water to flow normally with minimal head loss. As flow is reduced, the UFR returns to its operation of batching the water flow.
Water distribution systems are designed with the intention of the water flowing in a certain direction-- from the distribution system to the consumer. However, hydraulic conditions within the system may deviate from the "normal" conditions, causing water to flow in the opposite direction. Therefore, it is possible (and common) for water to flow from individual customer service lines back in the opposite direction. This is called backflow. Backflow has been known to cause contamination to pass into potable water systems, such that most states have regulations requiring backflow protection to be in place at each customer connection as a precautionary measure.
Backflow prevention values include, but are not limited to:
A pressure vacuum breaker (PVB) is a type of backflow prevention device, used to keep non-potable (or contaminated) water from entering the water supply. A PVB is similar to an atmospheric vacuum breaker (AVB), except that the PVB contains a spring-loaded poppet. This makes it acceptable for applications that are high hazard or where valves are downstream. Pressure vacuum breakers must be protected from freezing when installed outdoors.
An Atmospheric Vacuum Breaker (AVB) is a backflow prevention device used in plumbing to prevent backflow of non-potable liquids into the drinking water system. It is usually constructed of brass and resembles a 90-degree elbow with a hood on its top to allow air to enter the water system if a siphon attempts to form. Inside this elbow is a poppet valve that is held "up" by the water pressure found in the system, closing the air entrance to the device. If the pressure in the "upstream side" is reduced to atmospheric pressure or below, the poppet valve drops and allows air to enter the system, breaking the siphon.
These devices, since they work on atmospheric principles, cannot be installed in an enclosure containing air contaminants. Those contaminants could be drawn into the device, thus fouling the pipes. AVBs must be installed a minimum of 6 inches above the highest usage point in the system (i.e. sprinkler, drip emitter, etc.) Underground installation of AVBs is entirely ineffectual in providing backflow protection as groundwater in the underground vault could be drawn into the water system, contaminating it.
A double check valve or double check assembly (DCA) is a backflow prevention device designed to protect water supplies from contamination. It is also a valve used in air brake systems on heavy trucks. In water supply, the double check value consists of two check valves assembled in series. This employs two operating principles: firstly one check valve will still act, even if the other is jammed wide open. Secondly the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and avoiding even minor leakage.
Pressure reducing valves could be listed as a method to manage customer water use efficiency, since the water pressure within a home or business impacts the water used by fixtures, appliances and irrigation system. Most household fixtures and appliances operate best at a water pressure of about 50 to 60 psi. Too much pressure and appliance wear too quickly, hot water heaters may leak, and irrigation systems loose efficiency.
Installing pressure relief valves typically occur within the home or business on the main water line coming into the building/facility. Costs for the equipment range from $100 to 250, depending on the size of the service line (note that these are not boiler pressure relief valves which as less expensive). Installation is not included.