Not sure who to believe - advice for low dynamic water pressure

[csun]

I live in a 110yr old house that has issues with water pressure. The pressure is usable but a bit low when only one fixture is running, but drops quite a bit when two or more fixtures are in use. I've measured the pressure from a hose bib that branches off only a couple feet after the water enters the house. It reads 55PSI at rest, but drops to 35PSI when someone flushes the toilet.

The pipe running from the meter appears to be 1" or 3/4" galvanized and is visibly pretty corroded where it enters the house (pictured below). The plumbing inside the house is 3/4" copper that branches off to 1/2" copper at some points. The house is 3 stories if you count the basement too.

I've had two plumbing companies come out to give a quote on improving the water pressure issue, Company A (who we've used before) and Company B (who our neighbors recommended).

The plumber from Company A suggested installing a pump, but pointed out the galvanized water main and said that it was probably as old as the rest of the house. The next day, the plumber from Company B came out and said that installing a pump wouldn't help and that we should replace the water main instead. He said that it's very common in this area for these original galvanized water mains to have a ton of buildup to the point where it greatly reduces the internal diameter.

After this, I called Company A again to discuss replacing the water main instead of installing a pump. They sent a different plumber out to look, and he told me that replacing the water main would probably not help much and would not "give as much bang for your buck" vs. just installing a pump.

I'm not really sure who to believe. Replacing the water main is about 2.5x more expensive, so I'm not sure if Company B is just trying to sell me extra work. At the same time, it would make a lot of sense to me if reduced diameter of the main was the root cause of the pressure issues, and I wonder if installing a pump would just be a band-aid fix. I also don't really like the idea of adding in an extra component that requires maintenance / electricity.

The upfront cost is not really a concern to me - we could afford to replace the water main if that really is the "right way" to fix things. I just wanted to see if anyone on this forum might have some input on what's more likely to be a long-term solution to the pressure issues.

Thank you!
csun

 

[John Gayewski]

Your sooner or later going to need new piping so you could try that first. No matter what every fixture is going to like having new piping. I would suggest replacing as much galvanized as possible if you need a pump after that so be it.

 

[Sponsor]

 

[Breplum]

Your steel water main is obsolete/ end of life. It is the first thing worth doing. Then see.

 

[Master Plumber Mark]

Call the water company and have them read the pressure at your meter....

Some areas of older areas of towns have too small a system and the pressure is piss poor.....

If your incomming pressure is like only 40 psi then you are probably screwed


If the water service is 100 years old you are probably going to be doing this
new service sometime soon anyway.... that is murpheys law
If you do the pump first, then , odds are the main line will go bad on you real soon

perhaps you can get a one inch line run into the home for slightly more volume

I would call the water company first.....

we have installed this brand of booster pump on older systems and they seem to
work great and the main line has not failed yet.............

 

[wwhitney]

I've measured the pressure from a hose bib that branches off only a couple feet after the water enters the house. It reads 55PSI at rest, but drops to 35PSI when someone flushes the toilet.

This, right here, is proof that the galvanized water lateral is severely clogged. It says basically that whenever the system is flowing however much a toilet uses while it is refilling, your water lateral is dropping 20 psi. That's way too much. You could extrapolate from that to conclude that if you flush two toilets simultaneously, your water lateral would drop the full 55 psi, leaving no pressure for pushing flow through the pipes in your house. [That's not actually what happens, instead the two toilets refill more slowly, and your water pressure reading at the hose bibb would be just enough to push that amount of flow through the pipes from there to the two toilets.]

A pump will add pressure back. But it won't significantly increase the maximum flow you can get out of that galvanized pipe, you'll still be limited to no more than two fixture at once. And as the galvanized lateral continues to rust, that will become just one fixture at a time. So it's a short-term band-aid solution.

The only long-term solution is to replace the water lateral.

Cheers, Wayne

 

[Master Plumber Mark]

This, right here, is proof that the galvanized water lateral is severely clogged. It says basically that whenever the system is flowing however much a toilet uses while it is refilling, your water lateral is dropping 20 psi. That's way too much. You could extrapolate from that to conclude that if you flush two toilets simultaneously, your water lateral would drop the full 55 psi, leaving no pressure for pushing flow through the pipes in your house. [That's not actually what happens, instead the two toilets refill more slowly, and your water pressure reading at the hose bibb would be just enough to push that amount of flow through the pipes from there to the two toilets.]

A pump will add pressure back. But it won't significantly increase the maximum flow you can get out of that galvanized pipe, you'll still be limited to no more than two fixture at once. And as the galvanized lateral continues to rust, that will become just one fixture at a time. So it's a short-term band-aid solution.

The only long-term solution is to replace the water lateral.

Cheers, Wayne

Odds are he will probably have to do both....
pressure is pressure so he has only 55 psi incomming...to work with

change the main water line coming in....... then either you win or you
end up installing some kind of boooster pump......

I have a few customers in the midddle of town that installed a huge well type bladder
in their basement with a shallow well jet pump just to increase pressure and volume....
they installed a back flow valve on their incomming main line and it seems to keep things good...

remember that you cannot squeeze blood out of a turnip....

 

[Reach4]

If the fire hydrants are on your side of the street, it will probably be cheaper to get the water service line replaced than if the hydrants are on the other side.

As you and others observed, getting a pump is a point of failure or service. Also sound is generated by a pump. A pump takes space.

 

[csun]

Thanks for the advice, all. I really appreciate it. I'll try replacing the galvanized first and go from there.

 

[Fitter30]

Shut the the water off at the street pull union ( in basement)/apart and inspect both sides of the pipes. Copper started to replace galvanize in the 1960s.

 

[Valveman]

Yeah replace the pipe first. But then you still only have 55 PSI. If you want strong constant pressure a booster pump will be needed. But the larger pressure tank will make the pressure lower. Using a Cycle Stop Valve to keep the pump from cycling on and off a large pressure tank is not needed. With only a 4.5 gallon size pressure tank, like comes in the PK1A kit you will get strong constant pressure from the CSV all the time.

 

[John Gayewski]

For what its worth most of the entire town I live in has between 40 and 50 psi. There are no problems associated with pressures in that range. Only when the piping is too small does he pressure being below say 35 make that much of a difference.

In this case the old piping is being restricted by rust and other buildup which is effecting the flow.

 

[Valveman]

I agree 40-50 should be plenty. But if that is meter pressure and the house it plumbed with pex and/or has an upstairs, the pressure could get down to 30 or so at the shower. 60 PSI seems to be the most common set pressure for boosters that I see.

 

[Master Plumber Mark]

50 psi water pressure is easy on the water heaters stress wise,
but actually is a pretty wimpy amount

its basically about the same as well pressure..... it will work fine but still it is not "exciting or robust"
when you take a shower..... you are not gonna get blasted with water, its more like you are gonna
get pissed on......

the booster pump will help somewhat and get you up to probably 70psi
here is the one we have installed about a dozen times now

 

[Valveman]

Every pump company has one of those flow switch controllers that has to stick straight up from the pump. The flow switch falls back down to shut the pump off when flow is less than about 1/4 GPM. They are inexpensive and easy to install. But the reason pump companies use that type controller is that the pump only last a little past the warranty date. If you like selling pumps they are great. If you like happy customers, not so much.

Notice that no pump company has a version of the Cycle Stop Valve as they wouldn't get to sell very many pumps that way.