How To Drain an In-Ground Pool

WRITTEN BY:  Inyo Pools

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There are times when you may have 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.

Step by Step


Step 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.

Step 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.

Step 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.

Step 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. See our guide on "How To Add a Pool Waste Line".

Step 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.

Step 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.

Step 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.


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Inyopools  Posted: 10/22/2017 23:30 PM  Inyo Product Specialist

Joanna – Once your pump loses suction, you might have to use something like a wet shop vac to get all of the water off the bottom of the pool.

Joanna  Posted: 10/19/2017 20:07 PM 

I need help I don't how to get the water out that's left in the pool its 22ft 52inch I used a hose it didn't get all the water out

Inyopools  Posted: 08/28/2017 11:33 AM  Inyo Product Specialist

Harveyhelp - If you pump is partially submerged or surrounded by water, I would not try to run it. If you have any elevation, try putting one end of a garden hose in the pool and stringing the hose away from the pool. Fill the hose with water by blocking the free end. If the free end is below the pool end sufficiently, gravity will pull water out of the pool when you unblock the free end. If this works, it will drain faster with two or three hoses in the water. Good luck to you all !!

Inyopools  Posted: 08/28/2017 11:21 AM  Inyo Product Specialist

Mhunter321 - Most in-ground pools without Multiport Valves have a faucet inserted in the piping to release water to a hose. See Step 3 of "How To Add a Pool Waste Line". If your system does not have one, I would add a waste line into your piping to dump water. A near term solution would be to rent a pump to suck water out of the pool.

Harveyhelp  Posted: 08/26/2017 14:21 PM 

Help! I'm in Houston and my in ground pool is overflowing and almost at my back door! What can we do?

Mhunter321  Posted: 08/25/2017 16:49 PM 

Trying to drain my pool a lil but to avoid flooding with a pentair cartridge filter and having trouble doing it

Inyopools  Posted: 06/26/2017 17:21 PM  Inyo Product Specialist

Cyrataurean - We recently put out a blog on "How to Clean a Green Pool". It is a proven to work procedure based on heavy shock treatments and persistence. It will work for you.

Inyopools  Posted: 06/26/2017 10:37 AM  Inyo Product Specialist

valarie - It sounds like you have purged most of the old water out of your pool lines and equipment. What's left is not going to affect the quality of the new pool water much at all. I'd go ahead and fill the pool and let the chemical take care of the relatively small residue of old water.

Cyrataurean  Posted: 06/25/2017 21:47 PM 

I am in desperate need to drain my pool. It has been green for the past 6 months, at least. I have tried every and anything I can to clean it. I am to the point of literally draining it and start over. I have spent hundreds of dollars on chemicals and nothing has helped. Can I please get some advise, thank you.

valarie  Posted: 06/22/2017 22:01 PM 

I need help. I have an in-ground pool. Last year I drained it because I couldn't get it to balance properly.After sinking in over a 1000.00 in chemicals I decided it was best to drain it. What I didn't do when when I drained it was to close off the skimmers or the main drain. So over the winter it accumulated rain water leaves etc. I cleaned it out about a month ago and decided to paint the granite. it turned out nicely. my problem is, I know that there is still old stagnate water in the pipes. I used my shop vac to suck all that I could out be fear that there is still more in it. I don't want to refill the pool and start it up and the nasty water comes back into the pool. and make the water green or nasty all over again. My pool also has a heater which I'm thinking that there may be water in that also. I know I need to get all the water out but don't know how or where to start. Oh and I know there is water in the sand filter. I don't see any cut offs except for the skimmers and the main drain. My other fear is that it has been raining constantly for the past 2 weeks and the pool is empty and Im afraid that it may pop out the ground. tomorrow it suppose to b nice and no rain and would really like to get the pool started up again. My grands have been waiting for me to finish. I need help

Inyopools  Posted: 06/19/2017 15:00 PM  Inyo Product Specialist

h2o - I would empty the remaining water with a shop vac.

h2o  Posted: 06/18/2017 11:44 AM 

ive emptied most my pool but the last bit won't empty by the drain...just draws air.
can someone help please

Inyopools  Posted: 06/14/2017 10:33 AM  Inyo Product Specialist

Amanda - I'd leave the pump off until you refill the pool.

Amanda  Posted: 06/14/2017 8:19 AM 

I am only draining my pool halfway. Do I return to filter mode from waste after I am done?? Skimmer will remain off. Thanks!

Inyopools  Posted: 06/13/2017 19:15 PM  Inyo Product Specialist

Eddie - Take out the skimmer basket and block off the lower pipe with one of these "Rubber Expansion Plugs".

Eddie  Posted: 06/12/2017 19:29 PM 

I need help with Step Step 5, < CLOSING THE TOP SUCTION LINES >. My pool does not have a set of dedicated diverter valves. Is there a feasible way to cover the Skimmer to block sucking the air into the system when the water level drop under the "surface" of the skimmer? Tks!

Inyopools  Posted: 03/06/2017 11:32 AM  Inyo Product Specialist

Jojo - Unless you have a separate bottom drain that is independent of your main drain that goes to your filter, you really don't have an option. Most pools don't. When you do drain through the filter system, you have to avoid getting air into the system. You will have to have diverter valves to shut off the skimmer and the suction port, if you have one), so air isn't sucked into the pump causing it to lose prime. The lower levels of the pool water will have to come out through the main drain.

Jojo  Posted: 03/03/2017 11:56 AM 

I need some help. I am having my pool resurfaced. I have spoken to several pool companies they all said that they would drain the pool through my filter system away from the house, with the exception of one company. They drain the water out through the bottom drain into the ground below the pool. This does not sound right to me, putting 12,000 gal. Of water under my pool. Help ! Can it be done this way?

Inyopools  Posted: 12/19/2016 12:50 PM  Inyo Product Specialist

Chip - Make sure the slimmer valve is closed and if you have a suction port make sure that valve is closed too. Then add water through the pump's strainer basket to fill the pipes, close the basket and the pump should prime.

Chip  Posted: 12/15/2016 23:57 PM 

I need to empty our in ground pool for first time and forgot to close off skimmer valve on pipes when water got below skimmers and now pool won't empty, have I got air trapped in pipes? how can i fix that? Please!!

Inyopools  Posted: 09/19/2016 13:28 PM  Inyo Product Specialist

draining pool - Shut off any input ports that are above the current water line - these may include the skimmer and the suction cleaner port - so that you will not be sucking air into your system. Only pull water in from the main drain on the bottom of the pool. Fill the main drain line through the pump basket for five minutes. Close the system up and start your pump.

Anonymous  Posted: 09/18/2016 11:52 AM 

I ran into this problem first time in 21 yrs when draining pool for winter how can I get it resolved I drained to just half way on jets and had to stop it then a few days later wanted to drain more however lost prime and suggestions what to do I tried putting back to filter pressure increase some but then failed grr

Inyopools  Posted: 06/06/2016 11:49 AM  Inyo Product Specialist

TRR - "high waters" means high water table like most of Florida. If you live in Florida and are expecting a bad storm with heavy rain, I would wait for the rain to stop and the water to drain down before emptying my pool. Then I would try to get it filled again before the next rain.

TRR  Posted: 06/04/2016 21:24 PM 

My pool has the original water in it and it's gotten harder to maintain. I really cannot tell if i have equipment troubles or its just a build up of TDS. Having said that, this was the first winter I tried to cover the pool for winter. It was a fail. My pool looks like a cess pool. So rather than invest the time& money to get it back to blue, I think it would be a good time to drain & start over. Above you mention "high waters", what do ypu mean? If I drain it, I'll probably piwer wash & give it a good scrubbing and i can almost guarantee this will not happen in 1 day. How long is it safe to leave it empty? A week?

Inyopools  Posted: 08/15/2015 15:18 PM  Inyo Product Specialist

Mateo - Step two of this guide will have to be rewritten. We tried to cover cartridge filter with DE/Sand filters and they will have to be addressed separately. For cartridge filters, the return diverter valves will remain open allowing water to flow from the filter back to the pool. When you open the waste line, you will be tapping off water from the returning water. Therefore, water will be going to both the returns and the waste line. For DE and Sand filters with Multiport Valves (MPV), you will be rotating the MPV handle to "Waste" mode which diverts all water to the waste line. Any water that was going to the returns is shut off at the MPV. In neither case, do you have to adjust the diverter valves to the returns. Sorry for the confusion. Hope this helps.

Mateo  Posted: 08/15/2015 13:32 PM 

Am I understanding correctly that I need to close my return lines?
The explanation under step 2 confused me a little.