Low water pressure and supply

I recently opened a inbay touch free and 3 self serve carwash. I'm experiencing problems with water starvation. I have a 1 inch input and when RO system is filling it will cut on and off. The city supply pressure will drop from 55 to 10 psi. I would like to put a tank in the control room with a float and a repressuring pump. If anyone has some idea on how to do this it would be greatly appreciated. Currently i'm reusing the waste from RO piping drain to rinse tanks on auto and selfserve. Today I had to unplug ro and shutdown wash. City said they were filling swimming pool. 1 inch meter was all city would allow

In some cities it's illegal to pump and repressurize the incoming water. You might want to check into that if you'll have an inspector coming in to check on your boiler of backflow preventer.

A friend found a really nice system that uses a 5-gallon bladder tank and a pump on a VFD. The pump runs when it's needed and only runs fast enough to maintain a preset pressure. I think it cost him $2,200, but installation needs were very minimal due to the small size.

Thanks for the reply. The city is all for me to fix problem. I need to find this type of system and a detailed drawing of how it works that would really help. Thanks again

If your wash has tanks that fill from high volume valves, you can possibly buy yourself a little pressure by choking back the valve that goes to these tanks. An IBA pump might use 25 GPM, but the valve refilling the tank might be trying to draw water at 40 GPM or more. The same for the SS which 3 bays is only using about 12 GPM, but a BOB, Jobe etc. is filling the tank much faster than that. Try partially closing the valves on the lines feeding those tanks until the water just keeps up with demand. The hydrominders need at least 25psi to function correctly, but 10 psi residual pressure is plenty of incoming pressure for pumps. I have bypassed pressure switches before, but you do run the risk of burning up a pump if the water does get turned off.

Bob Koo here at TCW has a RO reject repressurization system that works with a VFD. It maintains a very steady pressure -I think a consistent pressure that stay within a couple of PSI.

Yes I see what you mean about refilling it does flow alot of water. I trimmed valve back alittle on self serve and auto. Pool was still being filled today but they cut valve back some. I would like to look at the RO reject system this would definitly help. How do I find Bob Koo? I will switch pages and see if there is a member page. Thanks

The way I have dealt with low water pressure problems at my sites is to install a booster pump with a bypass. The pump only runs if the incoming pressure is to low. Another aid for your water starvation on your iba would be to plumb the solution pump to the hotwater line you are using to feed the self serve. Since you no longer will need to use your solution tank to feed the solution pump you can tie the solution tank to the high pressure tank to increase its size.

Had a similar problem at my wash. I had something up the line that was blocking it. It would have pressure and the minute you needed water it would drop. Water company said it was something to do with my side of things. So I completely disconnected my in coming water turned it on and it came flying out for a split second then nothing. They had to blow air up the line and pushed whatever it was out of the line.

Just had a simialar problem. Checked water pressure on service side of backflow preventer and had 55 psi and 45-42 psi on my side. Pulled backflow preventer and did not find any restrictions. Called Watts manufacturing and was told should only have 3-4 psi drop. I'm going to pull backflow preventer out and connect straight pipe with guage and then see what happens. I hope the BFP is defective and this solves my problem. Trimming the tank fill valves back helped alot.

Did they ask you how much you were trying to flow through it?

In my former career we spent a considerable amount of time learning to compensate for pressure losses as water moved through hoses and piping. Even plumbers and water systems employees don't give this problem enough thought. I've seen quite a few car washes with undersized plumbing. People try to save on building costs, and copper bigger than 1" in diameter gets real expensive. The result can be plumbing too that is too small for the application. This can lead to inadequate pressure that impacts chemical mixing devices and creates problems such as yours.

Undersized water softeners eat up huge amounts of pressure at higher flows. Can't exactly recall but I believe water softeners have their flow rated for 15psi loss. Well, if you feed a softener at 50psi you could get 35psi coming out the other end. By the time you travel through some more plumbing you could be down to twenty psi residual pressure in high flow situations. That's too much loss IMO.

Not only do you lose flow and therefore pressure through an undersized softener, but the media can only fully soften water at a certain flow. A head that can flow 40 GPM on a small tank with enough resin to clear water at 15 GPM won't do its job properly.