Hello again, and thanks for your help. I am reposting an old problem. It seems every time I embark upon a water system upgrade, the hope of resolving this problem re-arises.

I have a small restaurant in Chicago. It is located in a house that is 100 years plus old. The main coming in is 1 1/4 inch. It runs into a new meter and then immediately splits into 2 inch brand new 1 inch copper lines which feeds the restaurant and the remainder of the house.

The problem is this: Everytime the commercial dishwasher goes on, the pressure in the all other taps goes down to a dribble, including the rest of the house. The DW is fed by a dedicated 3/4 in copper pipe which T's off the 1 inch, runs through a hot water heater, then into a pre-heater and finally into the DW.

Now in my own un-illumined mind, the DW has a pump which pushes water in at a higher pressure. It would seem that it "sucks" water out of the rest of the system when it pulls water, temporarily reducing the pressure, and therefore the problem would seem to be one of volume, maybe...somehow maintaining the pressure/volume in the remainder of the system when it goes on.

Since the DW has its own dedicated hot water heater, it should have plenty of volumne. Could the problem be solved by placing a reserve tank and/or a pressure pump to increase the pressure to the remainder on the remainder of the system?

Thanks for your thoughts/counsel.

Are you sure the dishwasher has a pump on the incoming water? That would be a rare situation. SOMEWHERE, and we have absolutely no way to tell you where, there is a restriction in the water supply and until you find it there may not be any solution. IF you installed a pump, and there was not enough water to feed it when the pressure dropped, it would cavitate and destroy itself. Call a good plumber to evaluate the system and see where the problem is.

The City of Chicago-Water Dept, delivers over a billion gallons of fresh water to its customers and 125 communities around Chicago... Daily.

Call the City Water Dept at 312-744-4420 and ask for a water usage and integrity evaluation to determine if 1-1/4 inch supply is enough for your building. If your building is not properly supplied, the City Engineers can advise you.

Best Wishes

Thank you. I guess its time to call a pro!



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