When it comes to plumbing your inground pool kit, the options are fairly simple. Included in every pool kit is a 100 ft. roll of 1-1/2" flex pipe, valves and fittings - enough to plumb a small and standard pool. Upgrades to the basic plumbing can be made in regard to Size of Pipe, Types of Fittings, Type of Pipe, and adding Additional Pipes.
Size of Pool Plumbing Pipe
Most swimming pools are piped in with 1-½” plumbing. This refers to the diameter of the pipe, although like a 2x4 piece of lumber, the O.D. of a 1.5" PVC pipe is actually more like 1.9". Using 2" plumbing gives you better flow and less resistance in your system, which means that your pool pump doesn't have to work as hard, or as long, each day. Plumbing your pool with 2" pipes and fittings, is the more energy efficient way of pool plumbing.
If you are planning on a large pool, or planning to use a variable speed pool pump, or have some thoughts about adding water features - these are good reasons to consider the additional expense of using 2" plumbing. It may cost an additional $500 for your inground pool project, but I believe that you'll see that return to you over time, by way of reduced electrical expense and wear and tear on the pump and filter.
If you are using 2" plumbing in your pool design plans, use it for both the suction and return piping, to and from the pool. You'll also want to use 2" piping above ground, in between the equipment. Even in places where the equipment may have 1.5' ports, like the pool skimmer, use a reducer to connect 2" pipe directly.
Types of Plumbing Fittings
You can reduce the resistance in the system even further by planning to use fewer restrictive fittings. In my pool installation last year, I used 2” rigid PVC pipes and tried to use as few 90 degree elbows as possible. I used two 45 degree elbows in place of one 90 in a few areas, and sweep elbows where ever possible. Sweep elbows are larger, and less restrictive than a true 90 degree PVC fitting.
Be sure to use Schedule 40 PVC fittings. Schedule 20 is too thin, and Schedule 80 is too thick. Sometimes schedule 40 is abbreviated SCH40, and you will see this printed on pipes and on fittings. You may also see it referred to as PVC 1120, and stamped with ASTM D-1785. Never use DWV fittings (drain, waste, and vent), they are not made for underground pool lines or for pressure systems.
Types of Pool Pipe
Flexible PVC Pipe:
We send 1-1/2" Schedule 40 Flexible PVC with our vinyl pool kits. Flex pipe is easy to ship and easy to use. If you desire, 2” flex pipe can be sent instead of 1-1/2", with a small upcharge. The flexible 2 “ pipe is more expensive than rigid PVC pipe, but you'll need fewer fittings because the flexible PVC can bend around corners, making sweeping turns in any direction, without using additional fittings, which add resistance to the system.
When using flex pipe to plumb in your inground pool, many DIY pool builders will still use rigid PVC pipe on the equipment pad. From the pool over to the equipment pad is usually plumbed with flex pipe, and then as the pipe turns to come aboveground, out of the trench, rigid pipe can be used. Using rigid pipe above ground will have a more finished look, and it can help to hold your equipment more securely.
Black Poly Pipe:
Underground black poly pipe can be used also but it is a little harder to work with as it is not as flexible as flex pipe. If you do end up using the black poly pipe you will need different fittings also. The fittings used with black poly pipe are known as barbed insert fittings, and require more work to connect them together. Use pipe dope around the barbs; push it into the pipe and double clamp it. Get it good and tight and put a little heat to the pipe with a torch and re- tighten it. Black underground pipe or poly pipe is definitely the cheapest option, but not as long lasting and not as energy efficient.
PVC Schedule 40 Pipe:
When you are using rigid PVC always use schedule 40 fittings. Rigid pipe is more expensive to use, but it is a harder and more durable pipe. It has a stronger resistance to pool chemicals than either flex or black poly pipes. If using rigid PVC, be sure that the pipe is fully supported underneath as you backfill, to prevent damage to the rigid plastic pipe. Also, because rigid PVC is not at all flexible, be sure to bury rigid PVC to a depth of 24", to remove problems from winter temperatures or shifting soils.
Adding Additional Plumbing Lines:
Another upgrade that you can consider at the early stages of planning your DIY pool construction project, is to decide whether you will want to add additional suction or return lines to the pool. Adding a second skimmer can be a good idea if you have a lot of deciduous trees near the pool. Additional return jets can be placed in the steps or swim outs, or maybe you might want to add a dedicated pool cleaner line.
Also, if you think that you may want to build a water feature, now or in the future, you can run an extra pipe. this pipe can just be stubbed up and capped off at both ends, ready and available for use.
In Conclusion: So to recap some of your pool plumbing options - for my pool, I used 2”schedule 40 PVC, purchased in 20 ft lengths to reduce needed fittings, and we used sweep elbows and 45's instead of 90's. This was a very good option for my pool and my equipment. It was not the cheapest way of plumbing the pool, nor was it the easiest pool plumbing we could have used, but it will be energy efficient and very durable. For more information on trenching, and tips on pool plumbing, see another post of mine on Inground Pool Kit Plumbing.
If you have any other questions about plumbing your own DIY inground pool kit, give us a call here at SPP - we can help you plan the pool plumbing with a design and cost that makes the most sense.
SPP Pool Expert