How to Winterize/Close an In-ground Swimming Pool

pool anti-freeze

I realize that in some places there is no need to winterize a swimming pool.  In areas where the winter temperatures remain mild, or even if a pool is indoors, there would be no need to winterize.  However, here in the northern part of the country it is important to take special precautions to protect your pool from the harsh winter temperatures.  As you may or may not know, when water freezes it expands.  If water freezes and expands within the plumbing of your swimming pool, there is the potential for severe damages, such as broken pipes or damaged pumps, filters, or heaters, that would result in very expensive repairs.

Just as an example, let’s say you have an in-ground swimming pool with one skimmer, two returns and two main drains.  With this you have a pump, filter, and heat pump.  Now, imagine that you have not taken any precautions to protect your pool from the winter temperatures.  With water still in the plumbing of the pool, the risk of that water freezing, expanding and breaking the pipes becomes very high.  With water still in the filter, heater, and pump, there is the risk of damaging that equipment and maybe so much so that in order to fix it you now have to bite the bullet and replace the entire pump, filter, or heat pump.  If a skimmer line or a return line breaks you are probably looking at a fairly significant cost to have someone come out, dig out the line, find the break and repair it.  Keep in mind that they may have to dig underneath any concrete sidewalks you may have around the pool in that area, or worse, they have to break up the concrete, repair the break, and re-pour the concrete again.  If that is the case, that repair cost has just increased a lot.  If the break occurs in the main drain line, then you are looking at another huge repair cost.  Being that the main drains are encased in either concrete or a pool base of some sort, you will have the choice of never being able to use the main drains again, which would reduce cleaning power, increasing the need to manually clean your pool and increasing the usage of chemicals (not recommended).  Your other option would be to drain the pool, remove the liner, bust up the base or concrete around the main drain, run a new line to the main drains, re-plumb the system, get a new liner, replace the concrete or base around the main drains, install the new liner, fill the pool again, and purchase more chemicals to balance the water once again.  That can all be avoided by taking the time to winterize your pool. (Winterize! Winterize! Winterize!)  I would also recommend paying a professional to do it.  There would be a bit more cost involved, but a reputable company will usually guarantee their work and will allow you the peace of mind knowing that the pool was winterized  correctly.  On the other hand, I know that the extra cost of paying someone to do the job every year is not preferable or possible for everyone.

If you are looking to winterize your in-ground swimming pool yourself, there are a few things that you should know and have.
First, you will need to have pressure plugs to plug off the lines, next you will need Antifreeze.  You can usually purchase pool antifreeze from your local pool store. If not, you will want to use marine antifreeze, and typically you will want to have one gallon for each component of your pool.

Now, it is a good idea to make some pipes that will be installed in the returns, and skimmer of the pool.  Having these will allow you to more easily evacuate the lines of water, and pour the antifreeze in.  For the skimmer pipe you will need a male adapter, piece of rigid schedule 40 PVC and a 90 deg. elbow.  For the return pipe you will need a threaded 90 deg. elbow, a piece of schedule 40 rigid PVC and a 90 deg. elbow. This set up is necessary for each return.  Be sure to glue all fittings together except for the 90 deg. elbow.  That one will need to come back off to pour the antifreeze in.  It’s really only there to direct the water back into the pool.
You will also need a blower of some kind, and it is important for the blower to have enough power to blow out the main drain line.  You must realize that there is an enormous amount of weight pushing down on the main drains, so your blower will have to have enough force to overcome that pressure otherwise you won’t be able to adequately remove that water from the main drains.  Once you have these items prepared, you will be ready to disassemble the plumbing.  On most newer pools, the plumbing will be done with unions installed.  These will allow you to disassemble and isolate each line more easily.  Next, you will remove the plugs from the pump and the filter to allow the water to drain out.  At this point, you will use your blower to blow air through the pump, filter, and heater. You will blow through them until only a light mist of water comes out.  In regards to the filter, you already have it draining through the plug, so at this point you will only need to remove the water from the multi-port valve.  To do this, first turn the handle to set the valve on recirculate.  Blow through the inlet, and stand aside as water will come out of the outlet side.  Once you get that light mist blowing through, you can now turn it to waste.  Again blow through it until a light mist comes out of the waste side.  At this point you have the valve dry enough to not cause any problems.  Remove the sight glass from the filter, and all o-rings throughout the system and place them in the pump basket for safe keeping.  You are now ready to blow out the lines of the pool.  You will want to make sure the pipes are installed in the skimmer and returns, with the openings above the water line.  Now is a good time to recruit a helper.  You will blow through each component from the pump side of the lines.  Typically the returns are tied together underground so when you start blowing through that line you will notice water coming out of each return.  Keep blowing through them, and you will notice that the water will stop coming out of one return first, we’ll call that return “A” and the other is return “B.”  This is when your helper comes in handy.  It will be their job to cover return “A” with their hand.  This will force the air to blow only through return “B”.  Once you get that light mist coming through return “B,” have your helper switch and cover return “B” to allow you to finish blowing out return “A.”  Trust me, it sounds more confusing than it is.  Once the water is free from the lines, remove the 90 deg. elbow of either one and pour in the gallon of antifreeze.  Put a plug in the pipe and begin to unscrew it from the wall.  Keep another plug handy, because once that pipe is free from the wall you will need to plug the opening as fast as you possible can. Repeat those steps for the other return.  Now, plug off the return line from the pump side as well, and you are ready to do the skimmer.  For this you just need to blow the water out of the line until you get that light mist.  Next, pour in the antifreeze and plug the pipe.  This pipe will need to be short enough so the skimmer lid can be put on but still long enough to stay above the water level. (This pipe will remain in the skimmer through out the winter).  At this point you will want to stuff the skimmer with something to take up as much space as possible.  Usually it gets stuffed with Styrofoam.  Doing this will prevent the water in the skimmer from expanding very much when it freezes.  Last but not least, it’s time to do the main drains.  In newer pools, there are two main drains in the bottom of the pool.  Again, they are tied together underground.  You will not be putting antifreeze in this line.  simply blow through the line until both drains begin to bubble.  Once they start to bubble, continue blowing through them for 15 to 20 seconds.  At that point you can quickly remove the blower and install the plug.  This step needs to be done quickly so that water doesn’t come back into the line.

If this sounds like a lot of work or something you don’t feel comfortable doing, I would recommend having a professional assistance.  It will save you the headache of having to do it and it will allow you to rest easy knowing that it was done correctly.  I understand that this is a lot of information, so if  anyone has any questions please don’t hesitate to ask.