Draining of your In-Ground Pool

Sometimes you need to drain your pool - for maintenance or to replace the water after several years of use. Over time, the TDS (Total Dissolved Solids) level in your pool water build up to the point where it's difficult to maintain chemistry. If your pool's TDS becomes too high, you will began to see mineral stains on the pool's walls and floor. Eventually, your pool's surface material might begin to deteriorate if you don't reduce the TDS. Since it can be extremely difficult to lower the TDS level, draining the pool and starting over with clean water is often the best solution. This guide shows you the process for draining your pool. A word of caution. If you are in an area with a high water, you run the risk of having your pool heave out of the ground, especially after several days of heavy rain. If this is the case, you might consider only draining half of the water and refilling it the same day.

1. CONSIDERATIONS - There are three main issues to consider when draining the water in your poo. First, closing off the return lines to your spa and pool. Second ensuring that as the water level drops, you do not allow air to be sucked into the suction lines to the pool. When this happens, the pool pump will lose prime and water will cease to flow. Third deciding where to dump the waste water. Each of these issues is discussed in the following steps.

2. CLOSING RETURN LINES - The water in your pool is typically cycling through your pool's filter and returning to the pool. In filter mode no water is being added to your pool so there is no need to shut off the return lines to your pool. A related issue here is if you were to close off the return line and only open the waste line, the waste line might not be large enough to handle the GPM pressure generated by the pump. This is especially true if you are draining your pool through a garden hose. This picture shows how the discharge valves would be set while draining your pool. The extra water features [spa fountain, spa jets and the lion spray heads] have been shut off so the water flow is from the pump/filter back out through the pool returns. The waste line will also be opened in the next step to purge the water.

3. OPEN WASTE LINE - SAND / DE FILTER - If you have a sand or DE filter, turn off the pump and rotate the handle on the multiport valve to "WASTE" mode. Make sure a waste line has been attached to the "Waste" port and turn the pump back on.

4. OPEN WASTE LINE - CARTRIDGE FILTER - If you have a cartridge filter, open up the ball valve to the waste line. If you only have a hose outlet to purge your pool water, you might want to consider replacing it with a 1 1/2" ball valve.

5. CLOSING THE TOP SUCTION LINES - When the water level gets half way down the skimmer opening, you will need to shut off the skimmer suction line to prevent air from being sucked into the suction line and shutting down the pump motor. If you have a suction port dedicated to a suction cleaner, you will want to shut that off also. Generally these suction lines are controlled by a set of dedicated diverter valves. Also, shut off the Spa drain before it completely drains the Spa and your system starts to suck air through the port. This picture shows the diverter valve settings for draining the pool. All incoming ports are shut except the main drain. Water flows from the main drain to the pump and then out the waste port.

6. CHECK MAIN DRAIN OPERATION - When you shut down all the suction lines but the main drain, make sure that the diverter valve to the main drain is open fully and that the drain is not clogged. If it is clogged, you will see a marked decrease of water flow through the pump's strainer cover. If the main drain is clogged, you might have to rent a submerged pump for a day to place at the bottom of the pool. It will have its own waste hose.

7. CHECK WATER DISCHARGE REGULATIONS - Many municipalities prohibit dumping water into the streets. The approved process is to dump the water down your home's sewer clean-out usually located next to the house or on the wall. Check with your local authorities for what's acceptable. If you do dump water into the sewer line, you run the risk of too much water flowing and potentially backing up into the house. It is recommended that you reduce the GPM into the clean-out to a maximum rate of 12 gallons per minute. If you are already operating off a ball valve, just close the valve down to half. If you are using the "WASTE" setting on a multiport valve, you might try adding a ball valve at the end of your waste port to reduce the flow.

If you have any other questions about pool and spa products please do let us know - we are here to help!

Leave a comment