Drain kits for above-ground pools have not been popular for many years, because automatic pool cleaners had taken their place. However, many local communities are now requiring that drains be installed for above-ground pools. Bottom drains assist with water circulation, which keeps the pool cleaner, since they are connected directly to the pool's filter. The job of installing the drain includes digging trenches and cutting into your pool's liner. Installing the drain correctly is a time-consuming operation that should not be undertaken without preparation.
Find the center of the pool, using a tape measure. If the bottom drain kit only has one drain, mark this spot with a marker. Many kits come with more than one drain, which must be separated by a few feet. These drains should be as close to the center as possible, while keeping their minimum distance from each other. This can be done by dividing the required distance by two and measuring that distance from the center mark on the pool liner. For example, if the drains need to be three feet apart, measure one and half feet from the center mark for each of the drains.
Dig a trench about six inches deep. The trench should lead out to the pool filter and be underground. Lay out the pipes and hoses. Verify the trench is level or slightly deeper, as you move from the center towards the filter. The trench should extend at least one foot past the end of the pool wall.
Connect the hose to the fittings and to the bottom drain. Use Teflon tape on all the threads. If the kit comes with clamps, attach those, and tighten to the fittings to hold them in place.
Tape over drains and screw holes before placing dirt back into the trenches. The tape will keep dirt out of the drains and screw holes. Do not use sand to refill the trenches. Sand will be added over the covered trench later. Concrete may be added around the drain heads to keep them from moving when water is added to the pool.
Leave at least six inches on the hose exposed---from the bottom kit---for hooking up to the filter. Longer lengths may be required in your area, check with local codes. Attach it to the filter.
Add layers of sand, as required. Verify that the top of drain---not the faceplate---is level with the sand and not below, as this will cause issues with drainage and filtering later.
Once the pool is in place above the drain, smooth the liner out against the drain. Cut your hole and attach the faceplate and gaskets. The hole should be as small as possible. Add a few inches of water to the pool, and observe for a few minutes to make sure there are no major leaks.