Tanks & Pumps · In brief
Keeping a Storage Tank Clean Starts Outside the Tank
Cleaning a water storage tank is mostly prevention: screened vents, tight lids and protected overflow lines keep contamination out, and any job that needs someone inside belongs to professionals.
By the Ranch House Water desk · Updated · 2 min read
A storage tank on a ranchette near Paso Robles, Templeton or Creston is open to dust, birds, insects and rodents unless its openings are sealed. The U.S. EPA's tech tip on storage tanks says those openings must be protected from birds, bats, other animals, insects, rain and windborne contaminants.
What keeps a tank clean?
Screens and lids. The EPA tip calls for 24-mesh non-corrodible screen on all vents, and for overflow and drain lines to carry 24-mesh screen or a sealed flapper or duckbill valve. Overflow lines should end 12 to 24 inches above the ground over a splash plate or rocked area, and should not connect directly to a sewer or storm drain. That advice is written for public water systems, so treat it as good practice for a private tank.
Walk around the tank now and then. Check that the lid is closed, screens are whole, and nothing is nesting near the vents. Sediment can also settle in storage and pressure tanks over time, the State Water Board's well owner publication notes. Test the water at the tap through an accredited lab; see testing your well water.
How often should a tank be cleaned, and by whom?
We found no official cleaning interval for private drinking water tanks. If sediment builds up or a test turns up bacteria, have the tank cleaned and disinfected by professionals who do this work. SLO County's disinfection instructions for private water systems were not available to us, so follow guidance from SLO County Environmental Health Services rather than a dose from the internet. When replacing a tank, general advice is to choose one certified for potable water (NSF/ANSI/CAN 61), though no state rule we located makes that mandatory for a private home.
Our story on water storage tanks covers sizing and placement, and hauled water for rural homes covers refilling a tank by truck.
Sources
- U.S. EPA — Sanitary Protection of Drinking Water Storage Tanks: Vents, Drains and Overflows — 24-mesh screens, overflow height
- OSHA — Confined Spaces — tanks as confined spaces
- State Water Board — A Guide for Private Domestic Well Owners — sediment in tanks
- SLO County Environmental Health Services — private water system guidance