Driving over a septic tank sounds a bit daunting, doesn’t it? Back when construction wasn’t as closely monitored, many houses had driveways built that way. However, it’s wise to challenge this now.
If you’re a homeowner with a plan to renovate your house, or a prospective buyer asking about that great property you found with this specific arrangement, keep reading to find out the answer to the question, can a septic tank be under a driveway?
Should I Put a Septic Tank Under My Driveway?
The short, simple answer is no. Installing a new septic tank under a driveway is more often than not a code violation.
It depends on your county, but most regulations require at least 5 ft between a structure such as a driveway, patio, or pavement and the septic tank.
Why Can’t I Build a Driveway Over a Septic Tank?
There are several reasons why choosing to put a septic tank under a driveway isn’t a great idea:
Strength
Septic tanks come in many shapes, sizes, and materials. Most residential septic tanks are made of concrete, polyethylene, or fiberglass, and they’re different from the septic tanks utilized in city sewage systems. In other words, most of them can’t withstand the force that a car driving back and forth will exert on their top.
Accessibility
Another aspect you should take into consideration is accessibility. Septic tanks usually require pumping every 3-5 years, depending on the size of the tank and the number of residents in the home.
Burying your septic tank under a driveway is not ideal in this scenario for several reasons:
- Completely covering your driveway with concrete or asphalt will block access to the tank, and breaking that concrete to reach the tank might cause irreparable damage to it.
- Adding a manhole cover to your septic tank for better accessibility further weakens the uppermost surface that supports the driveway.
- Even if your septic tank is sturdy enough to support a driveway for regular cars, it might not stand a chance underneath the very heavy equipment required to pump and clean it out and cave in under the pressure.
Evaporation
This is a problem that reaches beyond septic tanks only. The whole system depends on the process of evaporation to get rid of the effluent, which is the liquid portion of sewage.
Septic tanks are connected to a drain field via drain pipes that seep wastewater into the soil, and the permeability of the soil causes the water to evaporate.
Putting your septic tank underneath a paved driveway will “suffocate” part of the system. When water doesn’t evaporate at a rate proportional to the frequent use of the system, the tank will fill up and require pumping more often.
Buying a House With a Septic Tank Under the Driveway
Back in the 1960s and 70s, code regulations weren’t as strict as they are now, this led to many houses on the market having a septic tank under the driveway.
It’s necessary to have a septic inspector take a thorough look at the property you’re considering. That way you’ll find out the septic system arrangement, location of the septic tank, drain field, and how far the drain pipes extend.
If you do find the septic tank is located under the driveway, you have a couple of options:
- Ask the property owner to take care of the relocation of the septic tank and repair the driveway according to county code.
- Calculate the cost and ask for it to be deducted from the price of the property. Only choose this option if you’re willing to go through with the renovations yourself.
- Search for another property that doesn’t have this problem.
Ignoring this problem will only invite further problems since an overflowing septic tank will clog the drain pipes with solids.
Once that happens, you have no option but to tear down the whole system to pump the tank and install new drain pipes, and maybe excavate a new drain field.
This process is both expensive and time-consuming.
How Can I Keep My Septic System Running Efficiently?
A septic tank sewage system relies on several factors. One we mentioned earlier is evaporation, where the effluent leaves the drain pipes to the drain field and escapes through permeable soil.
It’s crucial to have enough surface area for this process to occur, especially if you live in a humid area as it delays evaporation.
Another important aspect is bacteria. In a septic tank system, bacteria break down solids turning them into a sludge that sits at the bottom of the tank.
This process reduces the volume of the waste product and keeps the system running smoothly without frequent pumping.
However, if you use the same septic system for laundry water, which most likely contains bleach and antibacterial detergents, you’ll probably need to pump your septic tank more often.
Flushing sanitary products, toilet paper, and cleaning wipes down the toilet will also shorten the duration between pumps.
Last but not least, make sure your septic tank size is proportionate to the number of residents frequently using the system.
Clogged drain pipes are a serious problem, and those can happen over a weekend of having guests over since bacteria can’t multiply that fast to accommodate any sudden increase in load.
Final Thoughts
Choosing where to place your septic tank doesn’t only affect its current use, but will also affect the value of your property should you sell it in the future. The question of strength, accessibility and sewage elimination via evaporation shouldn’t be taken lightly.
So, since placing a septic tank under your driveway will pose some problems with your usage and property value, it’s best to find another location for it.
You should always abide by the building code of your county, since choosing to ignore it will put you at risk of a hefty fine.
Those regulations are put in place for a reason, and it’s always advisable to be cautious when it comes to the structural integrity of your property.