Pressure Riser or holding tank?

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  • This topic has 4 replies, 3 voices, and was last updated 21 years ago by Avatar photoRobert Stephen Morton.
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    • #275355
      Avatar photoAndrew S. McKay

      I am trying to figure out if I need a pressure riser (such as an Amtrol RP-10HP) or if I need a holding tank to solve my water problems. I have low flow under load – so low that I really can’t do much else when the washer is running (and I use water saving shower heads, etc….)

      Here’s the situation. I have water from a local tower. My neighbors, who live much closer to the street than I, do not appear to be having any water pressure/flow problems. Most of the houses are maybe 75′ from the street…. I am 450′ from the street, and built 6 years ago (most of the other houses are 20+ years old).

      The builder ran 3/4″ line from the street to the house (doah!). I have not measured static water pressure, nor the pressure when I have a spigot or 2 running. I guess that I should do that, huh?

      I am guessing that my static pressure is “OK” (equal to the water main pressure, shouldn’t it be?), but my pressure drops quite substantially under flow – small pipe over a long length – can only push so much water down the pipe.

      I have talked to a couple plumbers. One recommended a pressure riser setup, while one said just a holding tank. I am confused. I have the Amtrol literature on the Pressure Risers, and they state a minimum inlet pressure of 5 psi – how do I figure out if I will have enough water to feed the pump? I would think that I would actually have negative pressure in the line with a pump – if the pump is sucking water fast than it can be supplied… How do you know if this will be the case?

      I’m also confused as to how a holding tank would do any good. Can the pressure that the tank is set to exceed the incoming water pressure? Is there some kind of check valve put inline with the tank, to isolate its pressure from that of the water line coming to the house? I mean, as soon as I start drawing water from the tank, how does is the tank going to maintain good pressure without some type of block-off from the water inlet? I assume these tanks are a bladder type setup, where you can pressuring the bladder with air, to maintain a relatively constant pressure. But as the tank empties, it will not be able to fill at the rate that water is being used.

      Hopefully someone out here knows what I need to do to determine what type of setup I need to solve my dilema.

      oh, this problems has been around since day 1 when the water was first turned on from the street to the house in 1995 – it is not something that has happened over time. I have finally gotten sick of dealing with it, especially now that there are 2 people living in the house instead of just one. It’s a 2 story house, down in elevation by about 25-50′ BELOW the bottom of the community water tank – I am not at a high spot by any means.



      [email protected]
      Elkton, MD 21921

      » This message has been edited by kook on 03 November 2001

    • #291782
      Avatar photokook

      OK, I have some pressures, as measured on the hose bib on back side of house (water comes in from front of house):

      Static: 48 psi
      Kitchen sink running: 40 psi
      Kitchen sink and bathroom sink running: 24 psi!
      Kitchen sink, bath sink, washer (warm fill): 6-7 psi !!!!!
      Washing machine only (warm fill): 16 psi

      Front spigot only: 26 psi
      Front spigot and toilet flush: 16 psi

      The house is a 2-story. Outside hose bibs are (obviously) on first floor.

      Hopefully this provides some usefull information?


    • #291783
      Avatar photoRobert Stephen Morton

      Mark. I believe your water supply is inadequate because of grossly undersized supply pipes.
      With a 450ft supply pipe & static head of 110ft your minimum supply should be 50kpa 7lb at the most disadvantaged outlet/with all outlets open. In Australia the minimum sized pipe for supply purposes would be 40mm or 1,1/2″, I would install 50mm or 2″.
      I also believe you are correct in that if you install a pump it will provide negative pressure in the existing 3/4″ line because of friction. if you were able to suck enough water through the pipe you then will also have a flow velocity within the pipes exceeding 3m/s or 10ft per sec.
      Is it possible to install a tank that can be filled through a ball valve from the existing supply pipe & then pump from the tank to your house?, If you can, may I suggest a constant pressure type pump or a pressure limiting valve to equalise pressure to your upper story.
      You will have to do the siphering to work out the cost differences between a good quality pump & tank including associated plumbing costs or alternativly replacing the 450ft of supply pipe.
      However it seems to me that the builder may have been grossly negligent in the installation of a supply that was inadequate for the purpose it was designed to serve, after all he is a professional?


    • #291784
      Avatar photokook


      Thanks for replying. “Is he a professional?” – LOL. I live “out in the sticks”, and he went bankrupt after building my place – good with his hands, but not the sharpest knife in the drawer.

      I’m looking at a budget around $1k (US) – that’s about how much of an annoyance the problem justifies me spending, at least at this time. I have not looked too much into re-piping the line, but I am starting to consider it. The only way I could even come near budget is if I rent a ditch-witch and do the trenching myself. It will still require professional assistance for connection at the street and at the house – plus, a backhoe will still be needed both at the house and at the street, for connection. Winter is approaching here, so this option will have to remain on the back shelf until Spring – so it looks like this project is not going to happen until then.

      The idea about the tank with a check valve seems the most realistic to me. How big of a tank though? I can get an 85 gallon tank for a reasonable price – it’s the same type of tank that would be used on a well-type water system – rubber pressurized bladder. How would this system work? I understand that the valve would be closed when the pressure in the tank is higher than the pressure in the line. What happens when I start drawing water from the tank? Could I starve the pump when I near emptying the tank (the only supply coming from the street, when the check valve is open)? If you could walk me through the operation of the system (i.e. how it works, in theory) that would be most appreciated.


    • #291785
      Avatar photoRobert Stephen Morton

      No mark I am not talking about a bladder type tank, I am talking about a open topped tank with an overflow. probably 500gal capacity or a couple of days capacity, you would have to check if this system is a Registered Air Gap for Backflow purposes in your area?
      The incoming water would go through a Ball Float valve to fill the tank, you would connect a pump to the outlet to give the required pressure. I suggested a constant pressure type pump to avoid the high & low pressure of a pressure switch type pump. This is very annoying while under the shower.


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