How to DIY a pressurized septic system (county approved)

* I am not a professional plumber, installer, or any of the above. I am simply a homeowner trying to share some knowledge I learned while I was putting my first (and hopefully only) septic system together. I am creating the guide that would have helped me do it faster. Thank you for reading and I hope this helps.*

To start off, the instructional video I made of the septic system overview is probably an overall better explanation. But if you are more of a visual-only person, hopefully this helps give you a glimpse at the scope of this project.

Youtube Septic system overview

When we set out to do our own septic system, I had no idea the amount of learning and growth that would come along with it. In here I will dive into how to do your own septic system. I will let you know though; I am not a machine operator or dirt work girl so I cannot help with that part. Everything else though, you should find it here ;)

We started with the drain field which is probably a little backwards. We hired a septic design company to take our bedrooms and soil type into consideration and draw us up some directions and the as-built.. Also it’s required in our county to hire a designer for an approved septic system. She answered many of my odd questions and dealt with the extra burden of letting the homeonwer DIY. 

 

From this, we know we have to do 6 67’ runs of 1.25” schedule 40 pipe for our drain field runs. We were able to submit our whole design to HD Fowlers (local plumbing supply company) and they sold us a whole kit that has the required specifications. This made life much easier!

I drilled a 3/16” hole every 60” for each run of pipe.

We used this 2 part primer and glue. The primer is bright purple, blue is bright blue.

 

We opted to use infiltrators, which are the black runs you see. They are about 3’ in length and you slide them over the previous one’s tang to snap it into place. Pretty easy honestly. We used zip ties at the end of each infiltrator and used those to hold the piping off the ground. (NOTE- if you are doing a gravel system, you need to not glue your lateral ends because for the test, you have the holes facing up but for final install, you want them facing down I believe.) At the end of each run, we had end caps where we finished the 1.25” pipe and (DO NOT GLUE) put the end caps with I believe an 1/8” hole to test for water pressure. Because the pipes were supposed to be at final grade, I left them extra long and planned to cut in place once the dirt work was done again.

At the ends, we drilled the hole for the 6” inspection port. This is basically just a piece of pipe with a tee at the bottom to prevent it from coming up and out of the infiltrator. (Pictured in the drawing) It does not connect to any of your other plumbing. Just there so you can open the cap and look at the end of each run.

I dry fit my end caps and staged the actual cleanout pipes at the end of the run for when the testing was done. I left them long because they are supposed to be at grade and I didn’t know what that would be. Figured I can cut them later but I can’t easily dig down and make them longer.

 

Next, we connected the loose ends through the front (shown above) and connected to the manifold. (see below)

 

Next, we cut holes in the green protective boxes to fit over the inlet and outlets of the manifolds. The manifold has a ball valve at each run. These are adjusted so that the water pressure is even in each run. When you do your test, your water will flow through the system and at the end of each run, you have that cap with the 1/8” hole (or different size). You will see literal streams of water coming out and up. The designer will want to get these all squirting at the same height. To do that, we adjust these ball valves. You may not have 6 runs, our soil isn’t the best so we had an insane drain field.

 

Next, we used the 2” piping to bring the plumbing up to where the septic tanks will be.

Next we had our two tanks installed. I had to have a pressurized system so it requires a holding tank and a pressure tank. You want to make sure the hole is perfectly level. I’m no dirt gal so I can’t comment on that other than to say, it was worth it to us to hire it out!

The next photo shows the two tanks in the hole and also leads into the next part. The plumbing in the tanks. Here I’m just getting a length to the drain field pipe and starting to build the more difficult part where the pump goes.

 

 

 

 

 

The top tank on the exit side of the house is pretty simple to put together. 

The inlet comes from the house and goes into the holding tank. It's just a tee with an extension going down. on the drawing it is the top left, also top left in the photo.

Next, it goes to the second half of the first tank through a pipe and hole in the concrete baffle. on the inlet side, its similar to the first pipe setup only a little longer. This acts as some kind of separation between the solids and liquids. Solids stay on the bottom and the liquid rises up high enough to make it to the other side of the first tank.

On the other side of the baffle in tank 1, is another tee that connects through the wall with a short extension.

Finally, in tank 1, the exit side goes out through a filter, into piping that leads to tank 2. Every 6 months you are supposed to pull that handle up and rinse out this filter. (gross)

The challenging part was the pressure tank. The plumbing comes over and for me, the bottom tank is flipped around from the drawing. It goes into the inlet from the right and over to the left is where my pump is. It made more sense to do it this way with where everything was. If these were orientated differently, it would have resembled the drawing. the inlet side was just a piece of pipe that connects to the pipe from the first tank. There are rubber collars that are part of the tank. the pipe from the other tank slides through and you just use a hose clamp, no glue, to fasten it. This is my only photo of the transport piping but it is just a 90, a stick of pipe, and another 90 going into the next tank.

Unlike the first tank, the second tank has a large void between baffles that allows the effluent to flow freely. I guess by this point it should be pretty liquid, so your pump won't be sucking up solids. No plumbing between the two sides is required.

Lets move on to the  pump side. To refocus, we are now in this part of the drawing.

The shroud mentioned at the base where the pump is, ended up being a 5 gallon bucket with holes drilled at 18” tall. The purpose of the shroud is to keep the submersible pump submerged in water in the event that there is no fluid in the tank. This prevents the pump from running dry and getting ruined.

Also shown in this photo is the Anti-siphon valve. I am pushing on the inside of the valve and able to open it with my finger, but no flow will come out of it. It is a 1-way valve, or a check valve. But in this application, it is an anti-siphon valve.  It is meant to prevent all of the water from emptying into the drainfield after the pump shuts off. It will not allow the water to push through but if there is suction, it will pull open the valve to interrupt the siphon.

*You may notice an extra piece of piping here. I made the mistake of making it too tall to be able to fit. I had to cut it and add a coupling since i had already glued it together.*

The service valve is just a ball valve. The check valve below just allows the water to go up but not down. You will also see the threaded union here. Very helpful if you have any issues with the plumbing in this area. 

 

On the right side of this photo is the float tower. The floats will rise up with the water level and have a switch in them that will send an electrical signal to your controller/alarm. The floats are all the same, where they are wired is the difference. The top one is placed so that if your pump fails and you have a higher water level than you should, it will sound off a very noisy alarm to let you know. The middle float is  given a longer lead. In its lowest position, it will tell the controller that it is a low level and cause the pump to shut off. The float on the bottom is a reduntant low level float. In the event that the low level float fails, the next float down will shut off the pump at a slightly lower level. This is designed to prevent the pump from running dry and getting damaged.

The floats have a hose clamp and a little rubber protector that goes around the cord and holds it to the plumbing stick. 

The next part was hooking up electrical. I’ll be honest, my father-in-law came over and did this part. Its honestly best to just watch the video on it if you have electrical questions. I will show you a couple photos of the internals. I have the 3 floats hooked up in here. The panel was fairly well labeled if you are decent with electrical work. We made sure to label the float wires accordingly. They then went underground through conduit and over through the tank riser into a water-tight box and into the floats themselves.

Also seen in this photo is where the electrical cord for the pump leaves the tank and goes through conduit and up to an outdoor power outlet. This outlet is wired to the control panel so that it only has power when the timer is on. All you see is the watertight box but inside is an outdoor receptacle that the cord is plugged into.

Next hurdle is the timer. I am glad my designer came out and helped me with this. 

It is set to run 2 minutes every 6 hours. It will do this unless the low level float trips the switch and shuts it off before the two minutes. The top dial is the minutes of run-time Looking at the Range on the left of the top dial, it is multiplied by "10M" or 10 minutes. So you multiply the 0.2 that the dial is set to by 10M and get 2 minutes. 

The dial on the bottom is similar only in hours. 0.6X10H= 6 hours. This is the duty cycle, meaning every 6 hours it will operate for 2 minutes of run-time. This was a bit tricky to grasp for me.

I am sure that the size of the septic system is what determines what your duty and cycle time should be. Ours is a 4 bedroom septic with a humongous drainfield. This is one of those things I would ask specifics to your designer on.

That is the level of depth I am going to go on the electrical. I am more detailed in the video I linked above as its much easier to pan back and forth with live video. I would recommend watching it. :)

 

Thank you for reading. I wanted to make the instructional that I wished I had to do this project. It’s likely you will have a slightly different setup if you go to do your own septic system, hopefully enough of this guide will apply to yours to get you through it. There are a bunch of other resources on Youtube as well 😊

Good Luck!