huge water pressure drop from sprinklers

rockstar

Hello,

Just bought a new house and have had some water pressure issues. As soon as the sprinklers turn on everything using water in the house barely works or doesnt work (sinks dribble, toilets wont fill, etc)

I tested our pressure and it registers at 88-89 psi. When we turn on the sprinklers it drops to about 21 psi, almost a 70psi drop!

Did the same test at our other house and we have 115 psi there, and the drop is only 10psi down to 105.

We also don't have very many sprinklers on each zone (all are rainbird 1800's). There are about 5 per zone, and they don't even pop up completely or spray out to there max distance (15').

Pretty puzzled on this one. our other home with the 115 water pressure, has large sprinkler heads (rainbird 2045's) on each zone and has excellent distance on each one (5 per zone) and no noticable lose on indoor pressure.

any thoughts or other tests are appreciated. thanks!

Canarywood1

As long as it's a new house,i'd call the builder and have him get it fixed.

dariusld

Maybe the house is new to him, but not new.

SPS-1

You posted this in the Landscaping Forum, but it seems more a question for the Plumbing Forum. I would not expect there is anything wrong with your sprinklers. The problem is that your house can not supply enough water. Sounds like your sprinklers and fixturers are being starved for water. What size is the water supply line to your house? Is the supply perhaps old galvanized pipe that is so full of rust that the water is flowing through a 1/4" orifice?

joecaption

It's a flow problum from under sized pipes not a pressure problum.
You old house had double the required pressure a normal single family home should have needed.
That high a pressure should have triped your water heater pressure valve and messed up the toilet flush valves.
Anything more then 60 PSI is just not needed.

Picture a garden hose with 60 PSI, now stand on the hose and open the nozzle no flow. Shut it off and the pressure goes right back up to 60 PSI.

rockstar

Yes it is a new to me house. but is 50 years old.

The pipe coming of of the meter to the house is 3/4". All the plumbing under the house is galvanized.

I might move this over to the plumbing thread..... but if there was some rusted pipe that was restricting flow, what would be the best way to test for this?

SPS-1

When you say 3/4" - you mean 3/4" nominal - 1.050" actual, right?

sdsester

I looked at the 1800 specs and they work from 15-30psi with 30 optimum and they are designed to balance themselves to average that. It is recommended you not exceed 70psi at the inlet but the point is pressure is not your major problem.

Now then, the flow rate of each full circle pattern sprinkler is 1.8gpm at 15psi and 2.6gpm at the optimal 30psi. You said you had 5 or so sprinklers on each irrigation circuit so your system is demanding 13gpm. That is more per circuit than most residential water supplies have available so switching pipe size is not going to help. You will need to re-arrange your sprinklers to have smaller circuits or switch the heads to something that draws less water. Obviously if you have hidden pipe breaks and leaking valves you are losing waterflow too. And if you have water flow blocked by deposits you lose more.

Once fixed, I would set the sprinklers to come on early in the morning before anybody is up and taking showers. It is a good time to water for the health of the lawn and you will not have competitions for water flow.

You can call the water company and they will tell you approximately how many gallons per minute they are pumping to your house. Or with a five gallon (or a gallon one) bucket and a stop watch you can come close yourself. Just turn off all the faucets and sprinklers. Put the bucket under a hose bib and crank the sucker full on until the bucket is full. Do some math to extend everything to 60 seconds. Here is an article that discusses the method.

http://inspectapedia.com/water/Water...re_Measure.htm

One thing you mentioned is that you have 115psi at the other house. That is excessive and puts a strain on residential plumbing systems. I would think about installing a pressure regulator to bring that down. 88-90psi is not so unusual but even that is high. Again the 1800s just as an example recommend a max of 70psi at the inlet.

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biggles

it's an open line...the main header line out to the sprinklers is open dumping the house pressure.... how is the actual sprinklers spray