I would like advice on how to set up a tank for a residential well.

A plumber has just installed so that it is pumped with the well head entering the bottom of an 800 gallon retention pressure tank. The water leaves the top of the tank and goes to the house.

I think that this is plumbed wrong: there's nothing compressible in the system, so the pump turns on and off continuously (it's set to swing between 65 psi and 45 psi, as I recall). Also, in case of electricity failure, gravity won't bring me water from the tank.

I think that this system needs a small bladder tank added. Is that right? Since I have an 800 gallon retention tank, can I use the smallest bladder tank available? Should the bladder tank be placed between retention tank and well head? That way any sludge can remain in the bladder tank, and the retention tank should remain clear. Also, can I then plumb the outlet from the retention tank from one of the bottom holes, rather than the top one, so that I will have 800 gallons available by gravity feed in case of power failure?

DETAILS

There are three residents, with fairly low water requirements (two toilets, two showers, dishes washed by hand).

Testing shows the well is 80' deep, max pump discharge 20gpm. Two hours of pumping in October (before rainy season here in Sonoma County California) drew the well down from 27' to 53'.

Before the plumber installed the retention tank, there was a quite small and very old (probably 1961) bladderless pressure tank, no retention tank. They had to cut the old tank to remove, and about 5 gallons of black sludge were in the bottom of the tank.


The water characteristics:

alkalinity: 120 mg/l
total hardness 16 gpg
total iron 1 mg/l
total manganese 0 mg/l
pH 6.8
total dissolved solids 280 mg/l
appearance clear
nitrate 3 mg/l
nitrite 0.2 mg/l

Thanks,

Bo