Poor Municipal Water Pressure Diagnostic FAQS

Index to all Q&A on Lost Municipal Water Pressure

Municipal water pressure drops in half and then returns in minutes: leak in the water system

We have been having an issue where the water pressure drops to about 1/2 speed after about 4 minutes of flow say in the shower then in 30 seconds ramps back up to full speed.

Does this on every faucet in the house. Had water department out twice, each time they see a 65PSI reading at the meter out in the street. Had a plumber come out today, his gauge showed 100PSI on the outdoor faucet initially.

Turned on faucets in the house and it dropped to normal 65PSI and waited till it dropped to 20PSI returning in 30 seconds. He had be contact the water department again.

They were able to replicate the same readings and confirmed that there was a problem.

She said they would raise the level in the water tower over the next 24 hours to see if that helps. Stating that they are losing water from an unknown source as well because the tower level is dropping. Doesn't make sense to me. On 2018-11-27 by Carol Dziatlik

by (mod) - Additional Diagnostic suggestions

Carol

That type of cyclic variation in water pressure is very similar to what we see when a booster pump somewhere is cycling on and off.

Are you sure there are no pumps, pressure tanks, and pressure controls on the water delivery system?

In contrast, when water flow rate or "pressure" is being affected by clogged pipes or pipe diameter the characteristic is good pressure only when water is first turned on, then pressure drops and stays down.

The other possibility to ask about is the effect on your water flow rate of other users on the water system turning their fixtures on or off. Depending on where you are in the distribution piping network your water pressure (flow rate) could be affected by other users.

Found blockage at Water Pressure Relief Valve

I had no water at the kitchen faucet. I disconnected the flexible pipe between the valve and the faucet.

Water came out of the copper pipe when the pump was on. So the blockage was between there and where the water comes out of the faucet. I removed the flexible pipe and decided to blow through it. It had been replaced about a year ago but it was actually blocked.

It was a sandy, salty deposit. I live in a desert town (Rocky Point, Sonora) and the water comes from a municipal well.

The blockage was at the valve end or easier end of the tube to remove so it would be easy to fix if it happened again.

What type of deposit was causing the blockage? Was It dissolved salts? It forms a coating on a small part of the floor of the shower which is difficult to remove. It is sand coloured. On 2018-01-27 by Brian Heeney

by (mod) - debris blocked valve cuts municipal water pressure

Thanks Brian for the comment - it will help others diagnose loss of water pressure.

I've previously pointed out the importance of removing and cleaning faucet strainers but I had not considered that a flexible riser between stop valve and sink faucet might itself be completely debris clogged -perhaps more likely when the line makes a loop or sharp bend.

Debris wants to collect in the low point of bends and elbows where it can eventually form a blockage. Just what "debris" is collecting depends on what's in the water: suspended solids, sand, silt, or in the case of hard water, scale formation.

Inadequate Water Pressure: Only 1 shower can run at a time: Is it our old water pipes or our pressure regulator?

100 year old home. We've had the problem for years of not being able to shower when someone else is running water. It's a small family, so we live with it. However, we now have a problem in which our new washing machine won't function correction. The specs say it requires a minimum of 30psi.

Testing at an outside spigot (there is no way to test where it enters the building), our city water appears to be at 70psi. Turning on one faucet, such as the washing machine, causes it to drop to 35 immediately. Which means it's probably closer to 19 at the washing machine (second floor).

When machine is stopped it immediately goes back up to 70psi. Turning on two (washing machine and shower) causes it to drop to 25. Three (washing machine, shower, and flush the toilet) drops to 15psi.

We have two issues we know of -- old galvanized pipe coming from the city main, and 1/2" copper pipe throughout the large old home. The question is whether the galvanized pipe is the problem.

If water replacement is the issue, why does it jump back up to 70psi immediately when the faucet is closed? Would a booster pump help, or would the pump just burn out or turn off because it can't draw enough water from the main?

There is an old corroded device just before the meter that may be a regulator, I'm not sure. It also might be an old shut-off valve with the handle broken off. It's too corroded to adjust, in any case. And I'm assuming a bad regulator would cause the pressure to go up higher than 70psi, rather than causing low pressure.

We'd like to avoid digging up the yard if possible.

We've lost too many trees in recent years, and this would certainly damage the roots of the ones remaining. On 2016-12-20 by Annie

Suggestion by (mod) - Measuring static water pressure outside shows that it's probably a pipe clog problem.

Annie:

Measuring static water pressure outside is fine for finding out what actual pressure is being delivered to the building. Make that test with no water running anywhere

70 PSI is plenty high. IN fact higher would risk leaks or might even be unsafe.

If you've also got good flow rate outside, then we know the problem isn't the water service main to the building. Just measure the time to fill a 5 gallon bucket and you can calculate the actual flow rate.

So the problem is more likely that a regulator indoors is defective OR that there are old clogged water supply pipes in the building.