Driving over a septic tank or its associated drainage field is not recommended. Septic systems are underground wastewater treatment structures that rely on the natural processes of anaerobic bacteria to break down and treat sewage.
Septic tanks, distribution boxes and drainfields (a.k.a. leach fields) are buried just under the surface of the ground, which makes them easily damaged by driving vehicles, or operating heavy equipment over them. Driving over a drainfield can cause the drainage pipes to crack, and create leaks throughout the system.
Avoiding Excess Weight on Your Leach Field
While many professionals believe that a leach field could bear about 10,000 pounds of weight for a short period of time, it's often not worth the risk. While you can safely walk on your leach field, parking, driving, and building on the area above should be avoided.
Grass is the ideal cover for drainfields. Grasses can be ornamental, mowed in a traditional lawn, or in an unmowed meadow. Or, you can try groundcovers and fems. The key to planting over the drainfield is to select shallow-rooted, low-maintenance, low-water-use plants.
In most cases, homeowners insurance does cover septic tank damage when it results from a sudden, unexpected event (as you might have noticed from the above list). However, home insurance is not likely to cover damage resulting from septic system problems caused by wear and tear or lack of maintenance.
People can stand on a kept-up drain field just fine. You could even set up lawn chairs and a folding table or two without fearing damage to your drainage system, but no structures or vehicles should be built or parked on or near a septic drain field.
The average cost of water backup and sewer coverage is $50 to $250 annually, depending on your risk exposure and the limits you select.
While a properly maintained drain field is designed to last up to 50 years, it's not likely that it will last much longer than that. If you're experiencing symptoms of drain field failure and you know that your drain field is getting up there in age, it might be wise to begin to budget for a drain field replacement.
You might wonder if occasional driving or parking would be okay. Unfortunately, even infrequent use can harm your drainfield. Unlike driveways or streets that are built for vehicles, your drainfield isn't designed to handle any kind of traffic at all. It's always better to play it safe and keep vehicles off.
You should never install the following over a drainfield:
Driveways.
Water leaks that overburden the septic system can lead to overflowing tanks, as well. Damage to the drainfield can also lead to standing water or poor processing of the effluent. Damage can occur if you drive over the field or if tree roots invade the field and cause collapse.
Generally no. Lawn tractors are okay, pretty much everything else is not. If you drive a pickup with a load of wood over your drain field you risk serious damage to the system. Please don't drive your boat and trailer across it either.
Generally speaking, septic drain lines are buried between 18 and 36 inches underground, and the pipes are surrounded by gravel and sand to aid in the filtration and water treatment process. Some septic drain lines may be buried just 6 inches under the ground.
Best Practices for Mowing Near a Septic System
We advise establishing a zone over and extending at least 10 feet around your drain field where you only plant grass and no heavy machinery rolls over it.
Reshape or fill the ground surface over the drainfield and reserve area. However, just adding topsoil is generally OK if it isn't more than a couple of inches.
The best plants you can put on top of a septic drain or leach field are shallow-rooted herbaceous plants. These include perennials, bulbs, turf-grass, weeds, groundcovers, and more. A few examples are holly shrubs, boxwood shrubs, azalea shrubs, hollyhocks, wild violets, and spring bulbs.
Driving over these components can potentially damage the system and lead to issues such as: Soil Compaction: The weight of vehicles can compact the soil above the septic tank and drain field, reducing the soil's ability to absorb and treat wastewater.
Typically, the drainfield consists of three to five trenches that are 18 to 24 inches deep, up to 100 ft long, with a perforated pipe in 12 to 18 inches deep gravel covered by 12 inches of soil.
A big risk to building over the drainfield is causing the lines to collapse. Also, the soil can compact around the trenches, which may not allow for percolation. Repairing the drainfield or moving it may require an entirely new system depending on your system age and the regulations for your local authority.
When the drainfield fails, or is saturated with water, sewage may backup into the home. Wet, soggy areas may develop above or near the drainfield and you may see spongy bright green grass over the area. There may also be odors near the tank or drainfield.
Based on 2024 prices, typical drainage costs per hectare are around: £2,500–£3,500 with permeable backfill.
While the terms are often used interchangeably, a leach field typically refers to the specific area where effluent is discharged into the soil, whereas a drain field encompasses the entire system of pipes and distribution components involved in wastewater dispersal and treatment.
While homeowners insurance protects you against some forms of unexpected water damage, water back-ups and sump pump overflows are usually not covered. You may purchase optional water back-up coverage that may pay for damages in the case of sewage back-up or a malfunctioning sump pump.
The water released by the treatment facility is usually cleaner than the drinking water's receiving stream. Typically, the advanced systems are expensive to build and operate, increasing the overall cost of wastewater treatment. So, it is logical that sewer bills are higher than water bills.
Residential Sewage Treatment Plant Costs
Overall, the average cost of buying and installing a domestic sewage treatment plant is around £7,000-£13,000. In some circumstances, you may be able to claim against your insurance's accidental damage policy.