static water pressure 40psi

[JoeTheStack]

Hi all,

Our static water pressure, measured with a gauge, with all faucets and bibbs off, is only 40psi. I checked it at several locations and it is the same.

Our water flow is also low, as you might have guessed. With the gauge on one bibb, and another hose bibb turned on and flowing, the static pressure at the first bibb (where the gauge is - there is no flow there) drops way down to around 15psi.

The house is located in unincorporated territory in the county of Los Angeles near Pasadena. It was built in 1944. As well as I can determine, there are no regulators or pumps or tanks involved, only valves.

It is a safe bet that some of the pipes are semi-clogged with mineral deposits. However, before embarking on a re-piping project, I want to confirm that it is the best solution, or determine a better one. So I am soliciting advice herein, and I thank you in advance for your time.

 

[speedbump]

Low pressure and flow could be the pipes and it could be the water supply its self. Maybe your at the end of the line where pressure would be the lowest.

A booster pump might help. I would try to borrow a small jet pump, install it in the main line and see what happens to your pressure with it running. If it works, all you need to add is a flow switch to turn it on when water is being used.

 

[chukar]

If your on city water they don't have to provide you with more then 15 psi, also if you gave a back flow assembly near your water meter that could be part of your issue. Before you commence with a repipe eliminate all other issues, if there a leak in the main before it gets to your house.

 

[JoeTheStack]

Low pressure and flow could be the pipes and it could be the water supply its self. Maybe your at the end of the line where pressure would be the lowest.

Thanks for replying! Please correct my following statements if needed:

With no flow, and no pressure regulator, the low pressure must be the water supply itself, neglecting to account for any elevation gain, which in this case is about 4'.

Low flow must be caused by one or more pipes being restricted somewhere. The pressure drop when water is flowing, at a modest flow, supports this hypothesis. So far we don't know where the restrictive pipe is - it could be the main feeder, or it could be all the pipes including the main feeder. The flow is lower at some faucets than others, but it is high at no faucets.

Is 40psi static considered abnormally low? I've measured it at other houses, not in this neighborhood, in three separate other locations around california, and those measurements were 85-95psi.

A backflow preventer especially if not working right could be a restriction to flow. But could a backflow preventer affect the static pressure when there is no flow? However, I have not located a backflow preventer. In the water meter area there appears to be only a meter and a valve.

I'll find out who our water company is. It is city of Pasadena, even though we are not in the city limits.

 

[JoeTheStack]

If your on city water they don't have to provide you with more then 15 psi, also if you gave a back flow assembly near your water meter that could be part of your issue. Before you commence with a repipe eliminate all other issues, if there a leak in the main before it gets to your house.

I haven't been able to locate a backflow preventer near the meter or elsewhere. I am aware that they are often required by code and/or water department. Maybe I should check with the water department to see if THEY think we have a backflow preventer, and ask them how to identify it. I am glad you confirmed that I should eliminate other possibilities before commencing a repiping!

Perhaps if the repiping were to include the main feeder to the house (the pipe on the house side of the meter) then adding a backflow preventer should be part of the plan.

 

[chukar]

If you have a water meter something to check, shut off every faucet, toilet, and water appliance, go out to your meter and watch the dials for 5 minutes look for any movement if your dial us moving with everything turned off good chance you have a leak. Next if there is a shut off valve inside or just outside your house shut it down and again watch the meter. This would tell if you have a leak from the main to your house.


The other method if you have no meter is still shut the water off at the city curb stop on the edge of your property put a pressure gage on a hose bib and watch it, if it drops once again good chance you got a leak.

 

[JoeTheStack]

It is a safe bet that some of the pipes are semi-clogged with mineral deposits. However, before embarking on a re-piping project, I want to confirm that it is the best solution, or determine a better one. So I am soliciting advice herein, and I thank you in advance for your time.

Here is a brief update, a bit belated. I ended up re-piping the house, and the low-flow problem is solved. The static pressure is the same.

I re-piped from the meter to the back of the house. I did not install any devices such as a booster pump. The old main supply pipe was not leaking yet, but it was badly deteriorated and wouldn't have gone much longer without leaking.

The new pipe is PEX and copper, mostly the former, replacing the old pipe which was the standard galvanized iron/steel pipe (I'm not sure of the technically correct ID of the material in that piping system -- is the tubing itself usually steel now, but the fittings are cast iron?)

Briefly, I ran a 1" supply line from the meter to the back of the house. I attached 3/4" tees which feed copper manifolds with 3/4" inlet and 1/2" outlets, and the water heater, also 3/4". Then I ran 1/2" lines to all the outlets in the house. I haven't been willing to open up the plaster walls as necessary to replace the risers, except the water heater which I replaced with 3/4" copper, and the outlets in the 1/2-bath I'm renovating. Except for those, all the outlets in the house still have their original risers, which are undoubtedly restricted by deposits, like the old pipe I removed. Even so, all outlets have adequate flow, and perhaps it will be greater when I get around to replacing the rest of the risers.

The existing shower (that I am not yet renovating) has the old standard H and C faucets, so there is no pressure or temperature compensation in the valve(s). Since the re-piping we can take showers without the flow dropping to a trickle or the water going cold suddenly due to other outlets being used! Mission accomplished. I guess its been 18 months since I finished it. Thank you all for your time and your advice, all of which was very helpful.

 

[frodo]

Joe, You do not have to open your walls to repipe your water piping..exxcept the shower.

drill a hole, 2'' in front of the back of the cabinet wall. stub the pipe up threw the cabinet floor,

install an ...Escutcheon then a straight stop, not angle stop

do this at the toilet and washing machine

 

[JoeTheStack]

Right on, I get what you suggested. Just come up through the floor instead of the wall. That is actually what I did with the water heater. As you indicated, I can't do that for the shower but I can for the remaining outlets. Except for the kitchen sink, which has a wall-mounted fixture and no shut-off valves. It's the same kitchen situation in a different house I take care of that also would benefit from re-piping.