Cisterns and Underground Vaults

Cisterns are large systems, generally holding more than 100 gallons, that can be installed either above or below ground.

Rooftops are ideal surfaces for cisterns to collect water from. These systems collect runoff and slowly release it over time, mimicking natural conditions.

 


Benefits

Cisterns and underground vaults may offer the following benefits:

  • Reduce runoff volume and peak flows
  • Decrease downstream erosion

 

What does your Cistern look like?

Typical cistern components can include:
 

  1. Storage container, barrel, or tank for holding captured flows
  2. Inlet and associated valves and piping
  3. Outlet and associated valves and piping
  4. Overflow outlet
     

What does your Underground Vault look like?

Typical underground vault components can include:

  1. Storage container, barrel, or tank for holding captured flows
  2. Inlet and associated valves and piping
  3. Aggregate storage layer (rock or gravel)
  4. Riser access pipe
  5. Native soils at the facility's base 
     

Inspection & Maintenance Activities

Activity Suggested frequency/schedule
Inspect for accumulation of sediment, litter, or debris at the inlet and outlet Monthly and after significant rain events
Inspect for accumulation of sediment, litter, or debris in the storage container Monthly     
Inspect for normal standing water use within the 36 to 96 hour timeframe following a storm event After significant rain events
Inspect for leaks or other damage to storage container Twice a year


BMP Fact Sheets in PDF format

Structural BMP Outreach Flyers (Educational Resources Page)
 

Contact

  (858) 495-5323

  BMP.Program@sdcounty.ca.gov

 

 

Maintaining My Structural BMP Home Page