Friday, April 9, 2010

Water Use in Restaurants and Supermarkets

Water is often taken for granted, but the cost of water is approaching a penny a gallon in some jurisdictions in the US, including fees for both water and sewer. Since a restaurant may use 3,000 gallons on a slow day and 7,000 gallons on a busy day, the dollars add up quickly over a year.  Grocery stores with fish departments, meat departments, deli, bakery, and produce may use even more water.

Both restaurants and large supermarkets have water softeners and filters for ice machines, beverage dispensers, and hot water, to be sure the water they use is pure and clear. Wasted water costs money in filters and softening in addition to the utility costs.  To save water, tactics include:

  • low flow toilets and urinals
  • low flow lavatories (0.5 gpm)
  • low flow hose faucets on pre-rinse sinks (2.0 gpm instead of 4.5 gpm)
  • reducing flow through ice machines 
  • reducing flow through dipperwells
  • ensuring that dish machine valves are leak-free
  • repairing leaks in faucets
  • adding pressure regulating valves to water services where pressure is too high

However, hundreds of gallons are used every night in after-hours cleaning, and none of the tactics above address this.  I recently measured flow using a transit time meter for 24 hours at a restaurant on a very high volume Saturday.  Transit time meters clamp on the outside of a water pipe and use ultrasonic waves to measure flow without interrupting service.   Data is collected every 10 or 20 seconds, and you can download it to a computer to graph usage over the course of a day.  Here is what my graph looked like using Excel:

A 1997 study asserted that 1% of water use in restaurants is used for cleaning.  From the graph above, however, we can see that over 600 gallons was used by the after-hours cleaning crew.  In my teens, I was a cook at a pizza and grille restaurant, and once we closed for the night, I had to help clean the kitchen. We used buckets, scrubbers, mops, and hoses to clean the entire kitchen at least twice and often 3 times.  I know from experience as well as from the actual data, cleaning a kitchen uses a lot of water.

If you run a restaurant or grocery store, consider finding your water meter and taking a reading at the end of the night before cleaning, and again before prep starts in the morning.  Subtract the two to get an estimate of gallons used for cleaning.   To manage this use on a regular basis, add a remote reader to the water meter and tie it to a web-enabled data logger to generate regular reports on your PC.   If you need any help with this, please let me know using the form at right, and we'll lend a hand.

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