How to Plumb an Inground Pool
Continuing our series of how to build an inground pool, we now reach the phase of plumbing your pool, to connect the pool suction and return fittings to the filter and pump system. At this stage, the pool is dug, the walls are erected, and the pump and filter system are in place, on a level slab of concrete or pressure treated wood.
There are different types of piping that can be used for plumbing an inground pool. Most popular is schedule 40 PVC pipe. Schedule 40 pipe is available in rolls of flexible PVC or as rigid sticks, either 10 or 20 feet in length. Black Poly pipe, also sold in rolls, can be used. Black poly pipe will use barbed fitting inserts and clamps to connect to the pool and equipment, rather than glued PVC fittings.
The most commonly used pipe for inground pool construction is the 100 ft roll of flexible PVC pipe (1.5″ diameter). Having a continuous roll makes it easier to wrap around corners and you will need fewer connectors. If you purchased your inground pool kit from SPP, the Deluxe or Deluxe Plus pool kits come with everything you need to plumb the pool.
SPP Pipe & Fittings Kit includes:
- 1-1/2″ x 100′ Schedule 40 Flex Hose (1)
- 1-1/2″ PVC White Tee (4)
- 1-1/2″ PVC White 90-degree Elbow (5)
- 1-1/2″ PVC White Coupling (4)
- 1-1/2″ Male Adapter (4)
- 1-1/2″ PVC 90 degree Street Elbow (4)
- 1-1/2″ PVC 90 degree Street Elbow (4)
- 1 Quart Ultra Grip Blue Cement
- 1 Quart Purple Primer
Also included in our DIY inground pool kits – two 1-1/2″, 3-way Jandy valves and the Hayward Pool Plumbing Pack (widemouth Skimmer, extension collar, vacuum plate, 2 Returns, 2 VGB Main Drains). With these supplies, you are ready to start plumbing your inground swimming pool!
Plumbing the Main Drains:
New main drain safety laws require the use of dual main drains, to prevent entrapment on a single main drain. Dig a small hole in the bottom center of the floor, and place the 2 main drains, 3 ft apart from each other. Run a bit of pipe between the 2 drains with a Tee fitting in the middle of the pipe. From the Tee, connect a pipe that will run through the deep end slope, up underneath the wall. Once outside of the wall, run this pipe all the way back towards the filter pump. Connecting your main drain pipe into the skimmer is not recommended; this method won’t allow you to adjust the suction of the main drain and skimmers independently.
Plumbing the Skimmer:
If you haven’t done so already, connect the Hayward widemouth skimmer to the wall panel with the cut-out. Connect a pipe to the rear hole of the skimmer, leave the front hole plugged. Use Teflon tape and silicone sealant on the fitting, and tighten securely, but don’t over-tighten as you risk cracking the skimmer body. Connect the pipe to the fitting at the skimmer bottom, and run this pipe back to the filter pump.
The next step is to connect the skimmer line and the main drain line into the pump. Install an MTA (male threaded adapter) fitting into the front port of the pool pump. Use a proper thread sealant so there won’t be any air leaks. Once the MTA is installed, glue a 6-12″ piece of rigid PVC pipe, into the fitting. Glue the other end into the port labeled “Inlet”, on one of your 3-way Jandy Valves. One the other two side ports, glue in the 1-1/2″ Street Elbows, with the opening pointing down to the ground. Finally, connect your pipe from the skimmer and main drain into these two Street Elbows.
Some people building their own pool will use rigid PVC on the plumbing that is visible above ground, which looks a little better, and can provide more rigid support. If you want to do the same, cut the flexible pipe at the bottom of the trench and glue it into a SlipxSlip elbow fitting which points up toward the street elbow you glued into the Jandy Valve. In between these two elbow fittings, use a piece of rigid, schedule 40 PVC. Lengths of rigid PVC can be purchased at any home store, or plumbing supply house.
Plumbing the Returns:
The 24″ sand filter that is included in our Deluxe inground pool kits will have a multiport valve that mounts on the top of the filter tank. This valve has 3 ports, one labeled Pump – connect a pipe from the pool pump into this port, and one labeled Return – connect a pipe from this port towards the port labeled “Inlet”, on your other 3-way Jandy Valve. Using rigid pipe for these connections will look better, but is not required.
Coming out of the 3-way Jandy Valve, at 3 o’clock and 9 o’clock, you will again glue in two Street Elbows, pointing straight down to the ground. Glue two equal lengths of rigid PVC into these Street Elbows, and on the other end, into two slip elbows. Then glue your flex pipe into the other side of the elbows, and run your pipe to where the two returns are located, typically on opposite sides or ends of the pool. From your filter system, choose the shortest route around the pool, to reach the wall returns.
If you have more than two returns or two suction lines, you can add another valve, either a ball valve or a 2-way Jandy Valve, onto the return or suction-side manifold. Using a valve is important on each line, so that you have the most control over where and how your water flows.
Plumbing a Pool Heater:
If you have a pool heater you would do the return side plumbing a little differently. We will plumb the return side the same way, except that coming out of the multiport valve port labeled “Return”, we first run the pipe in and out of the heater. From your filter to your heater (or heat pump) and then out of the heater to your return side Jandy Valve, where the water splits into the two separate return lines going back – “returning” to the pool.
Plumbing Other Pool Equipment:
Our Deluxe pool packages include an Off-line chemical feeder. To install this you only need to drill 2 small holes in the return pipe. If you are installing a saltwater chlorine system or an In-line chemical feeder – you would install these after the filter, and after any pool heater, on the return line – before the return side Jandy Valve.
If you add any water features such as a waterfall, or deck jets, or equipment like a slide or a pressure-side (return-side) pool cleaner – these will be fed water from the return side as well. Typically, a tee fitting is installed on the return line, with a valve below the tee fitting, to control how much water is delivered or pumped to the device. Alternatively, instead of a tee fitting and a 2-way valve, you can install another 3-way Jandy Valve to control the amount of water delivered to other equipment.
Pool Plumbing Tips:
- Measure twice – cut once.
- Dry fit your pipe and fittings before cleaning and gluing.
- Make straight pipe cuts with a sharp hacksaw.
- De-burr the pipe after cutting, using rough sandpaper.
- Clean the pipe and fitting immediately before gluing with PVC pipe cleaner.
- Apply PVC glue liberally to both fitting and pipe, and quickly join, with a twisting motion.
- Hold the joint together for 10-15 seconds before releasing.
- With a wet cloth, wipe off any excess glue.
- Use a layer of silicone (I like Blue RTV) on threaded fittings, then 3 layers of Teflon tape, in a clockwise direction.
- Don’t over-tighten threaded fittings into pump, valve, skimmers, drains. Hand tight, plus 1-1/2 turns with large pliers.
Plumbing with Black Poly Pipe:
Black Polyethylene pipe can be purchased in long rolls, and is joined together using barbed PVC insert fittings, which are secured by stainless steel clamps around the pipe. Before inserting the fitting, apply pipe dope to the barbed fitting and insert the fitting deep into the pipe. Double clamp the pipe over the fitting with two clamps going in opposite directions. Tighten securely with a nut driver, then heat the pipe slightly with a torch. While still hot, tighten again on the clamps to improve the seal.
Black Poly pipe is not glued together like PVC pipe. Because of this, the joints are more likely to cause leaking problems years down the road. This is why some builders scoff and scorn at the idea of using Black Poly pipe. If however, you decide to use Black Poly, try to use as few underground connector fittings as possible, to reduce this possibility. The advantage of Black Poly pipe is that it can be purchased more cheaply than PVC pipe. This can save a few hundred dollars on large pool installations.
As described above, some DIY inground pool builders will use Black Poly underground, up until the equipment pad, and then come up out of the ground with rigid schedule 40 PVC, for a more secure and professional looking filter system installation.
Pressure Testing your Pool Plumbing:
If you want to be sure that your pool plumbing job was done well, without leaks – before backfilling over the pipes, you can pressure test the plumbing. This is done after all plumbing connections are complete, including the filter system plumbing. Allow the glue to cure for 24 hours.
Builders will usually have a homemade PVC pressure testing stick with a gauge. This is connected to the skimmer, and then all the other ports (main drains, returns, etc) are plugged at the pool using rubber expansion plugs. An easier method than building a pressure stick is to buy a Drain King. Available at most home stores, you connect this to a garden hose, and push it into the skimmer. Plug both drains and returns, open all valves. Open the air bleeder on the filter to allow the air to escape. Turn on the garden hose and the plumbing will fill up with water. Carefully check the entire run of plumbing for any leakage. It should be water tight, not even a drop should be discovered. Congratulations, now you can backfill over the pipe and up against the walls.
I hope that this little article about how to plumb and pressure test a swimming pool has been helpful and informative. Pool plumbing is not hard to do, just be sure to plan each section of pipes and fittings. Thousands of homeowners just like you have figured out how to build an inground pool, from pool guys like me. Plumbing an inground pool is one of the fun parts of building your own inground pool – enjoy it.
Happy Pool Plumbing!
SPP Pool Expert