13 February 2012

We can no longer waste water like Romans

I wrote this guest post for the water quality and security blog (please comment there):

Around the world, urban water suppliers use similar technology: the pipes, pumps and valves that move water from central treatment plants to household taps. These pressurized systems are not that much different from the systems that Romans used to supply water to their fountains and baths, with one exception: the Romans left their water running all day and all night. Few of us leave our taps open these days, because water is increasingly scarce — and we don’t want to pay a huge bill for massive volumes of water flowing through our household meter.

But that doesn’t mean that taps aren’t open somewhere else in the system that serves our houses. Leaking pipes drain our water supplies all day and all night. They reduce the water we have for emergency situations, and they increase the bills for everyone who has to pay for water. Water prices are set to cover the total cost of treating and distributing water, even if half that water is lost to leaks.

The industry uses the term “non revenue water” (NRW) to refer to water that’s lost, stolen or not paid for. System losses are usually the largest component of NRW that ranges from 5 percent in a “tight” system to 60 percent or more in decaying systems with poor management of revenue and water flows.

Most water managers know their NRW statistics. Some of them act to reduce NRW — by plugging leaks, metering all users and collecting payment — because they want to run an efficient operation, but others don’t care: why work harder if they can just push more water through the system? That response is not very satisfactory to customers who have to bear an unfair share of the system costs; it’s even less popular to people who worry about the impact of greater water withdrawals from the environment.

Indifferent managers usually pay more attention to NRW when their supplies are limited or when water is expensive. Scarce supplies make it profitable to spend money plugging leaks, to avoid building a desalination plant, for example. Higher prices create three impacts. First, paying consumers use even less water, increasing the impact of NRW (30 units of NRW in total sales of 100 units gets more important if paying consumers lower their use from 70 to 50 units). Second, higher prices mean it’s worth spending more to reduce NRW. Third, higher prices mean paying customers put more pressure on managers to share system costs more widely.

There are many ways to reduce NRW. Some of them require better measurement tools; others require changes in operating techniques. It’s interesting that expensive water gives both consumers and managers the incentive to change their technologies and techniques, as each group seeks a way to reduce, respectively, the cost of their household water and system inefficiencies.

Bottom Line: The end of abundant water means that cannot just run the taps like Romans. We need to close the taps, plug the leaks and make sure that everyone pays for his water use.

Addendum: SD and I had the following discussion over the post:

SD: NRW is a toy for managers; it's not economically sound or sustainable. Take, for example, a utility with 1 million connections and daily production of 300,000m3. If it loses 100,000m3 per day, it loses $50,000 per day (production cost $0.50/m3), or roughly $15 million per year. That may seem high, but it's only $15 per connection per year. Why repair pipes at a cost of $100s of millions to save so little?

Me: You should reduce NRW to avoid spending more on new supplies (if they are even available).

SD: But it's cheaper to ration customers, as they do in Jordan, Lebanon, Syria, Libya, and countries that do not believe in water prices

Me: That's inefficient if it's command and control. If there's price rationing already, then NRW reductions are STILL cheaper than more supplies.

SD: But CnC rationing costs the government nothing; customers bear coping costs, and they are happy to get a drop of water!

Me: Arg!