One well serving two residences is considered a 2
Single-Family Residential water supply. Three or more
connections are regulated by Article III of the Thurston
County Sanitary Code as a Group B public water system.
The pump should be capable of producing a
minimum of 800 gallons per day. A minimum 20 psi at maximum demand should be supplied to each property line or residence.
The pressure tank(s) should be sized so that the drawdown provides adequate pump protection and/or storage.
Pump protection: 2.5 x pump rate = gallons. (This is the minimum drawdown capacity of the tank.)
Prior to use, the newly constructed supply should be disinfected with a chlorine dosage of no less than 10 parts per million (ppm) as measured
after a contact time of 24 hours (10 ppm is equivalent to approximately 1 quart chlorine bleach per 1,000 gallons water).
Develop a Shared Well Agreement between
the two parties.
Evidence of well and waterline access agreement
filed with the Thurston County Auditors' office if
the two respective parcels sharing the well are
separate legal lots of record.
Test for coliform bacteria every year and
nitrates every 3 years.
NOTE: Expansion of a 2 Single-Family Residential water supply to provide additional connections will require the
supply to meet all the requirements of
that apply to public water systems. This includes a design of the proposed system
expansion by a qualified professional engineer and subsequent approval by the Health Department. For additional
Public Water System Design Supplemental Application[PDF].
and Additional Resources (some
documents are in PDF format, unless otherwise noted)
The following are frequently used forms:
Well Site Inspection
(both Supplemental and Master Applications required)