8.5 Meters, Water Loss Control, Asset Management & Customer Service

8.5 Meters, Water Loss Control, Asset Management & Customer Service

The WPI Water Distribution Class I outline lists metering and related equipment (remote readers, meter replacements), conducting meter reading, implementing a water loss control program, understanding elements of an asset management program, maintaining an up-to-date map (GIS) and addressing customer inquiries. These tasks keep revenue flowing and reveal problems in the system. ADEM's monthly operating report rule (335-7-10-.06) also lets the Department require water production records, distribution pressure measurements and water loss information.

Meter Types

Reading Meters

• Registers read in gallons or cubic feet; 1 ccf (100 cubic feet) equals 748 gallons. Check for a multiplier on the register face.
• The low-flow (leak) indicator turns with very small flows. If it moves when every fixture is off, there is a leak on the customer side.
• AMR (automatic meter reading) collects reads by drive-by radio; AMI (advanced metering infrastructure) uses a fixed two-way network to deliver hourly or more frequent reads with leak, tamper and reverse-flow alerts.

Example. Last month's read was 4,832 (ccf register) and this month's is 4,846. Use is 14 ccf, or $14 \times 748 = 10{,}472$ gallons.

Meter Accuracy and Testing

$$\text{Accuracy (\%)} = \frac{\text{Volume registered by meter}}{\text{Actual volume through meter}} \times 100$$

If 10.0 gallons pass through a meter into a calibrated test tank and the meter registers 9.6 gallons, accuracy is 96.0 percent and the meter under-registers by 4 percent, which is lost revenue. AWWA standards expect new displacement meters to read within roughly 98.5 to 101.5 percent at normal test flows, with wider tolerance at minimum flow. Large meters should be tested in place on a schedule because a small error on a large meter costs more than many small-meter errors. Replace meters on a planned program rather than only when they stop.

The Water Balance and Non-Revenue Water

AWWA Manual M36 organizes the annual water audit:

$$\text{Non-revenue water} = \text{Unbilled authorized} + \text{Apparent losses} + \text{Real losses}$$

Example. A system's input is 120 MG per year. Billed authorized consumption is 98 MG and unbilled authorized is 2 MG, so water losses are 20 MG. If apparent losses are estimated at 4 MG, real losses are 16 MG. Non-revenue water is $2 + 20 = 22$ MG, or $22 \div 120 \times 100 = 18.3$ percent of input. The Infrastructure Leakage Index (ILI) compares current real losses with the unavoidable minimum for the system's size and pressure; a lower ILI is better.

Finding and Reducing Leaks

• Acoustic listening on valves and hydrants, leak noise correlators and permanent noise loggers locate hidden leaks.
• Night-flow analysis in metered district areas shows leakage when legitimate use is lowest.
• Pressure management with pressure-reducing valves lowers leakage and break frequency in high-pressure zones.
• Repair leaks quickly; the volume lost depends on how long a leak runs as much as on its size.
• Storage overflows are real losses; fix altitude valves and level controls.

Asset Management

Asset management means knowing what you own, its condition, its risk and its life-cycle cost, then planning repair and replacement to deliver an agreed level of service at the lowest cost.

1. Inventory every main, valve, hydrant, meter, tank and pump in GIS, with size, material, age and location. Tie valves and fittings to permanent landmarks.
2. Assess condition with break history, inspections and test results.
3. Rank risk as likelihood of failure times consequence of failure; a transmission main under a hospital ranks higher than a 2-inch main on a dead end.
4. Plan maintenance, rehabilitation and replacement in a capital improvement plan with funding.
5. Track work in a computerized maintenance management system (CMMS).

Valve and hydrant programs are core asset management. Exercise valves on a schedule (critical valves more often), recording turns, direction, condition and location; operate and maintain hydrants at least annually (Section 8.2).

ADEM's storage tank rule (335-7-7-.04) is an asset management requirement too: each system must keep a written tank maintenance plan with an inspection and cleaning schedule not to exceed five years (Section 8.1).

Customer Inquiries

• Pressure complaints: check nearby pressure readings, recent valve work and the customer's pressure-reducing valve or meter strainer.
• Discolored water: often follows flushing, main breaks or valve operation; flush the main and advise the customer to run cold water.
• Taste and odor: check chlorine residual and recent changes; consider the customer's plumbing and water heater.
• High bills: re-read the meter, check the leak indicator, look for running toilets (dye test) and irrigation leaks, and test the meter if the customer requests it.
• Record every complaint with date, location, type and action taken, and keep the file for three years (Rule 335-7-10-.05).