Hi All,

I have noticed since turning my sprinkler system on for the summer that there is a significant water pressure drop in the house when I'm watering the lawn (usually in the morning while I'm taking a shower). I've lived in this house for 9 years and aside from the occasional maintenance nothing significant has changed and I've never encountered water pressure problems like this. I don't have any data from previous years but here are the current details:

- static water pressure is 75 psi (city water supply)
- bucket test showed water volume of 6 gpm
- water pressure while watering lawn is 20 to 30 psi (regardless of zone and sprinkler
Heads won't even come all the way up out of the ground)
- water pressure after a toilet flush is 58 psi
- water pressure with the tub filling is 55 psi (cold water)
- water pressure running a new water saver shower is 68 psi

The 6gpm seems low to me. At the moment I'm suspecting a volume supply issue coming into the house but wanted to do a sanity check before calling the water department. Any other thoughts out there?

Thanks,
Jim

"At the moment I'm suspecting a volume supply issue coming into the house but wanted to do a sanity check before calling the water department."

There's no doubt in my mind that this is a volume problem. The pressure's a little high, 45PSI is the norm but I believe if you put a gage on the water service where it enters the house you will find the pressure's steady and the loss is in your system. How old is the house and what material are the pipes? Regards, Tom

Hi speedball1, thanks for the response. The house was built in 1950. Supply line from the street looks like cast iron or something 1 1/2" or so. It goes into the water meter where it is reduced on the house end only to open up again to an 1 1/2" copper pipe that services the sprinkler system. Sprinkler system is probably 15 to 20 years old. The house line is off a T and looks to be 1" or so copper. Something like this:

valve to house (1") valve
___ | | +-------+ ___
| | | 1" | meter | |
-++------++-----------+ +---++-------+
+------------+--------+ |
-----------+ +-------+ |
to sprinkler (1 1/2) | |

from street (1 1/2)

Meter says 1" S.R 100 cu. ft.

They laid a new water main in our street several years back. At the time I didn't ask to have my service line to the house replaced. Maybe I should have.

I assume somebody from the water dept could come out and check things at the street end?

Thanks again,
Jim

Well, that picture didn't work out. How about this:


valve to house (1") valve
___ | | +-------+ ___
| | | 1" | meter | |
-++-----------++---------+ +----++-----+
+------------+--------+ |
--------------+ +-------+ |
to sprinkler (1 1/2) | |

from street (1 1/2)

Oh well, forget the picture. Sorry about that.

If your house was built in the 50's,(like mine) then chances are you have galvanized piping. Iron oxide, (rust), builds up in the pipe walls cutting down on the volume carried. As you make more demand on the system,( draw more water) the volume drops along with the pressure. I have the same problem at my place. If In were in your place I would take a pressure reading at the meter first with the house and sprinklers off and then with the sprinklers on and a shower or tub running. If the pressure held steady I would take the same readings where the water service enters the house. If there's an pressure drop when things are running then the service's suppect.This would give you a pretty good idea of what shape the water service's in. Let me know, Tom

Thanks Tom. There is a drain just on the house side of the water meter. I hooked up my pressure gauge there and it reads 73 psi. When I turn on the sprinklers and tub it drops to 18 psi. Sounds like the service. Thanks. Jim