If you're looking at a house for sale that has an existing septic system, you have to be sure that the septic system is in good shape. If the system is not in good shape, you could end up having to pay a lot more for the property overall because of the repair costs. You should always have a home that you're considering for purchase inspected by a professional, and you should also have the septic system checked out. But there are also a few things that you can look for that can give you a few hints as to how the system is doing without an inspection.
Green Patches Over the Tank
If the septic tank is working correctly and containing the solids, it's still going to let the liquids out, but it should let them out in the leachfield portion of the septic system, not right around the tank. If you see very green grass over the tank, ask if the ground there was just reseeded. Inspectapedia notes that if the green grass isn't the result of reseeding, there could be a leak around the tank cover or the pipes could be failing.
There should not be any trees over the septic tank. If you ask where the tank is and someone points at a grove of trees, don't buy the property. However, you might see trees near the area where the tank is, and this is where you have to be careful. Some trees do better near the tanks than others. The problem is the root system of the tree. If the root system is aggressive and fast-growing, and the tank starts to leak, the roots can invade the area where the leak is, further damaging the tank. Angie's List notes that some trees, like eucalyptus, birch, pepper, sycamore, and others should not be planted near the tank. If you see those, be prepared to remove them. If you can't identify the trees, have a landscaping company or certified arborist check them out.
This may sound like a strange one, but check out how access to the tank and field are restricted. Are there fences around along with no-trespassing signs? If the field is located in an open area that people can access from the road, you do have a risk of someone stupidly driving over the tank because they think they can take a shortcut through your property. This is more of a rural issue than anything else -- someone with a septic tank in an old suburb isn't likely to have that much open land -- but it is a risk. The weight of the vehicle can crush portions of the tank if the tank is not built specifically to withstand the added weight.
It's always best to have the septic system inspected before you buy, so talk to septic maintenance companies about quotes and times. The septic system is a significant part of your home's maintenance, and if there's anything wrong, you need to know before putting any money down. For more information, talk to a professional like Linn Septic Service.