Post-fire septic frequently asked questions

Can I get a site map of where my septic system is located?

If a septic permit was recorded, a copy of your septic system design (as-built) can be obtained by submitting a Santa Clara County Public Records Request

Will my septic system be ruined if I don’t use it for an extended period of time?

A standard septic system that was working properly and then not used for a period of time, such as 4 – 5 years, typically does not lose effectiveness or the ability to function properly once it is put back into use. Some of the older septic systems may even benefit from non-use by allowing some of the biomat, which is a biological clogging layer in the leachfield, to naturally break down and the soils rejuvenate. Septic systems with gravelless chambers used for leachfields are more prone to becoming less effective over time when they are not in use. This is because gravelless chambers are like long open tunnels underground that without wastewater flowing through them burrowing animals, like moles, can enter into them and begin to fill them with soil. Septic tanks, whether made from concrete or plastic, typically do not degrade or lose effectiveness when not in use. It is best to keep septic tanks full with water when they are not in use. This is because most empty septic tanks are not designed to withstand the exterior forces that are placed upon them from surrounding soil and groundwater when they are empty.

Do I need to pump my septic tank to be able to re-use it?

No, however a septic tank is recommended to be pumped when it is over 1/3 full of solids. Solids are the sludge and scum that over time accumulates in a septic tank. When a tank is inspected, a certified specialist will measure the sludge and scum and then make appropriate recommendations for pumping it. Unless the septic tank is undergoing a repair or an evaluation it is not necessary to be pumped. If it is a plastic septic tank and is pumped and will be used in the future, it should be immediately refilled with water. The same is true for a concrete tank, although a concrete tank can be re-filled within a week and typically not have any damage risk.

Can I use my existing septic system if I place a new home on my parcel?

Yes, if the system is undamaged, working correctly and was originally constructed under permit issued by the County. If a proposed fire rebuild includes additional square footage or an altered floor plan, the septic system may need to be further evaluated to ensure that the system can accommodate the proposed changes.

How do I determine if the septic system is undamaged and working correctly so that I can use it for a new house or structure?

All septic systems that were serving a structure that was burned or damaged must be inspected by a certified wastewater specialist, whether a septic pumper, designer, installer or qualified service provider. This certified wastewater specialist must be hired by the owner and the inspection must occur after Phase II debris removal is completed. A building division permit cannot be issued until the septic system inspection report is submitted. A septic system is not required to be inspected if it is to be used for temporary housing allowed under the county urgency ordinance.

What if I am rebuilding my house in a new location, will I still be able to use my septic system?

It depends. Most septic systems rely on the houses sewer outlet pipe being higher than the inlet port of the septic tank. That is so the wastewater can flow from the house to the septic tank via gravity. When a new house is built and the sewer outlet is lower than the inlet to the septic tank a lift station can sometimes be used. A lift station is a small holding tank with an automatic pump that pumps the incoming wastewater out of the holding tank and into the septic tank. A lift station must be installed under permit issued by the County Building Department.

If the fire damaged my septic tank, do I have to replace the whole septic system?

No. Only that portion of the septic system that was damaged must be replaced. Typically, a septic system is comprised of a septic tank and a leachfield. Each can be replaced separately when needed. When either is replaced, that portion must be brought into compliance with current Santa Clara County code and the work performed under a permit issued by the Department of Environmental Health.

If the top of septic tank is damaged, should I repair it?

At all times safety concerns must be addressed with damaged septic tanks. If the top of a septic tank is damaged, typically the inside of the tank is exposed. This poses a safety hazard for people and wildlife for falling into the tank. It also exposes people to the unhealthy wastewater inside. A septic tank that has undergone this kind of damage is required to be removed or destroyed in place. This is done under a permit issued by the Santa Clara County Building Department for unincorporated areas of the county. Typically, there is no effective method of repairing the top of a septic tank that has been damaged by fire, whether it is a plastic or concrete tank, and a repair is not allowed.

If my septic tank is outside of the ash footprint, what should I do with it? Should I wait until debris removal is complete? Should I cover it?

Typically, all septic tanks are located at least 5 feet from the edge of a building and are buried underground, so most septic tanks are outside of the ash footprint. There is no immediate action that a homeowner needs to take in regards to their septic tank, except to identify its location for the debris and ash removal crews who will be working around the site. If the tank is damaged in a way that poses a safety hazard for falling into, then immediate measures should be taken to remove that hazard. Laying down a large piece of plywood over the open hole is a recommended method for addressing this hazard. Caution tape should also be placed to alert people of the hazard. As previously indicated, a damaged septic tank is required to be removed or destroyed in place, but this will typically be required after debris and ash removal is completed.

Feedback form