On 7/26/11 12:00 PM, Brooklyn1 wrote:
On Tue, 26 Jul 2011 08:58:21 -0700, "Bob F"
wrote:

Brooklyn1 wrote:
David E. Ross wrote:

My neighborhood is on a water system that is gravity-fed from a
1,000,000 gallon tank up on a hill higher than any house.

That's typical.

The pressure in my lines is high enough that a hose turned on full
will writhe and snap like an injured snake.

Is "injured snake" some new water company standard?

Your water company like every other US water company is delivering
residential properties no more than about 40 psi, with volume limited
by meter diameter. Most folks on private wells will have much greater
pressure and volume than what a municipal water company supplies
residential customers... you'd be doing good if your tap can produce
four gallons a minute. With most neighborhoods on a municipal water
system it's suggested to run automatic sprinkler systems during the
wee morning hours before people awaken for the day, and then to have
no more than 4-5 sprinkler heads per zone.

Seattle city water pressure at my house is 70 psi, certainly well above "no more
than about 40 psi".

How do you know that you have 70 psi water pressure inside your home,
people on city water don't have a pressure tank. Most residenses
(especially older homes) would spring leaks at 70 psi... clothes/dish
washer fill hoses, ice makers, toilets and such especially... of
course you can post the Seattle water URL that shows their residential
pressure. Municipal water companys typically supply about 50 psi to
residential street mains but the residential meter reduces pressure to
about 40 psi, which is more than enough pressure for the average home.
Municipal water companys don't supply higher pressure than is
adequate, they are averse to destroying peoples homes.

We have a pressure regulator where our service line from the meter
enters the house. Thus, the house might have 40 psi.

However, our hose bibs and garden sprinklers are on a line that taps the
service line before the pressure regulator. I believe that line is
getting whatever pressure is in the main in the street. With a
1,000,000 gallon storage tank that has a base about 100 feet higher than
my house and that is ususally at least half full (another 30 feet), we
get about 130 feet of "head" or about 56 psi in our garden line.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary