We purchased a house here in East Texas 5 years ago. The disclosure stated the system was 5 years old. A few years later the neighbor who used to live here said no, it's 20+ years old as there used to be a single wide where the house is.
Worked fine until the third year it backed up.
Had it pumped but some water was coming back from the drain field.
Guy said it's a problem.
Year later.. lots of rain... backed up again.
This time alot of water kept re-filling the tank.
I used my Honda water pump to stay ahead of it.
Had the septic guys evaluate.
Here's the thing. Here in Texas you can do anything you want outside the cities. This system only had one very long field line.
A proper design would split it up into four branches coming out of a junction box. This way if one branch clogs you have the others.
They took a hand auger and took a sample of the dirt. He said too much clay. These guys don't need much to know the deal. The ground is similar all around here.
Recommended going to an aerobic system with sprinklers. This system is widely used in the region due to the ground type.
I asked him about perk test and he laughed and said the same hole will perk in dry times and not perk in wet times.
So $8k later we are running an aerobic system. I must say it's a non issue except for the one time the float switches in the 3rd tank where the submersible pump is to spray the field came loose from the pvc riser. The wires need to be attached to the riser within about 12" so the float flips up and down as the level changes. With the wire unrestrained, the float just floats around on top of the water.
They used regular tie wraps and then black tape over the tie wrap.
They deteriorated from the bleach. Not only that, there are two float switches. One to activate the pump and a higher one to activate the alarm. Since they both came loose at the same time the alarm didn't work either LOL.
I asked the guy why they didn't use a more durable attachment he said boss doesn't buy anything but this. I said you just spent way more on this free service call than would pay for hundreds of stainless steel tie wraps LOL. I have some SS tie wraps if it happens again.
Long story longer.... gophers dig burrows and create passages for ground water to infiltrate the drain field. In times of a lot of rain, there are a couple of gopher holes that become geysers LOL.
Oh forgot to say there is a bleach dispenser in the last tank that sanitizes the water before spraying. The bleach dispenser is simply a pancake shaped 2 gallon plastic container under the third lid. The cap is accessible from above. You simply keep liquid bleach in it and it automatically dispenses as the tank level goes up and down by means of the syphon effect.
I get bulk bleach for about $2 a gallon at Atwoods. Uses about a gallon every 2 months at most.