Should You Specify Solid-State Technology in your Next Meter Changeout?

Everything you always wanted to know about solid-state water meters (but were afraid to ask).

It’s hard to imagine a more critical component to a water utility’s financial health than the water meter. First invented by clockmaker, Thomas Kennedy Sr., the meter stands as the accountant of consumption, which in turn, delivers revenue to the utility.

Mechanically-driven water meters use the kinetic energy in the flow of water to measure consumption. It’s proven technology, cost effective and has served water utilities for over a century. Few solutions enjoy such longevity. Mechanical meters are affordable, proven, serviceable and have benefited from improved engineering, manufacturing and quality control over the past century.

A new breed of water meter is establishing a foothold in the market

However, one shortcoming of mechanically-driven water meters is that components within the meter wear during use. It doesn’t always result in a failure — the meter still works. It simply measures less accurately. As it turns out, this error favors the consumer. The under-reading progresses as the meter ages. In an age of encouraging conservation along with reconciling utility costs against consumption, it becomes difficult to get an apples-to-apples comparison from customers with identical service connections. Generally, the customer with the newer meter is billed more accurately than the customer with the older meter.

Sensus' iPERL

Sensus’ iPERL

This phenomenon becomes more significant as the service connection size increases. Commercial customers ordinarily account for the bulk of a water utility’s revenue. Consequently meter inaccuracy in larger connections can mean significant revenue loss to the utility, plain and simple. Factoring variables such as billing rate, typical consumption and meter age and associated asset management considerations, utilities find a sweet spot where the cost of replacing or servicing the meter is justified by increased billing revenue.

Assuming consistent consumption, this results in billing that approximates an inverse saw tooth wave. The new meter measures consumption accurately, the billing begins high. As the meter ages, billing slowly declines due to under-reading. When the meter is replaced, billing shoots straight up to the peak again.

As any utility that’s gone through a meter change out can attest, this results in a barrage of calls into customer service challenging the new higher bill.

Another limitation of mechanical meters is their ability to measure low flows. According to the AWWA Journal, about one-sixth of the time water is flowing through a meter, the flow rate is under one gallon per minute. (Apparent Losses Caused by Meter Innaccuracies at Ultralow Flows, Richards et. al, AWWA Journal June 2010). Unmeasured flows means unbilled consumption.

A new breed of water meter making is establishing a foothold in the market. Solid state meters—using  no moving parts—solve many of the shortcomings of traditional mechanical meters. These new meters use one of three technologies to measure flow.