If you have a pool in an area that sees winter weather, you’ll need to winterize it to protect the equipment. Specialized antifreeze in the supply lines can stop pipes from bursting, but what kind should you use, and how do you add it safely? We’ll share more about anti-freezing your pool in this guide.
How Does Pool Antifreeze Work?
Pool antifreeze usually contains a chemical called propylene glycol, a non-toxic substance that lowers water’s freezing point. This helps prevent water in your pool’s plumbing lines from freezing and expanding, which can lead to burst pipes that are costly to fix.
Another advantage of antifreeze is convenience. You don’t need specialized equipment to add it, and it removes the need to blow out or drain the pipes with compressed air each fall.
If your pool has an in-ground vinyl liner, you’ll need to be especially diligent about using antifreeze. When groundwater seeps into unprotected pipes and freezes, it can warp the vinyl liner behind the pool wall when it expands. That can lead to unsightly wrinkles and may even require replacing the liner.
What Kind of Antifreeze Should You Buy?
With so many antifreeze products available, it can get confusing to choose the right one. However, you should always find a non-toxic formula that’s specifically designed for pool systems.
Automotive antifreeze uses ethylene glycol, which is a toxic chemical that can react with the chlorine in pool water. Instead, choose a propylene glycol-based RV antifreeze or a commercial pool line antifreeze product. Check that the solution is concentrated and not a weaker premixed version. The concentrated product has a lower freezing point to handle particularly cold temperatures.
You’ll also want to purchase food-grade polyethylene glycol designed for drinking water systems. Industrial-grade antifreeze may contain questionable additives.
Look at the manufacturer’s specifications to confirm the antifreeze protects down to the appropriate temperature based on winter lows in your climate zone. Using an antifreeze rated for -50°F provides protection even during an extreme cold snap.
Can You Make Your Own Antifreeze for Pool Lines?
At anywhere from $15 to $30 per gallon, pool antifreeze can get pricey, especially if you have long supply lines. Theoretically, you could make your own antifreeze to save money, but it’s a risky process that requires precise measurements and chemical handling. Doing it the wrong way could be ineffective at best or dangerous at worst.
If you’re interested in the idea of making your own antifreeze, talk with a chemist or pool specialist about how much propylene glycol you should use and the type of water that’s best. You should also learn the proper procedures to store and dispose of the chemicals.
Remember that pool line antifreeze will eventually end up in your pool water. Never try to cut corners by substituting auto antifreeze or any other product with ethylene glycol. Even in low concentrations, the ethylene glycol can react with chlorine to form toxic chlorinated hydrocarbons.
How to Add Antifreeze to Pool Lines
Adding antifreeze to pool lines is a straightforward process that you can typically handle yourself. Here’s how to do it.
- Know how much you need: Plan on using two to three gallons of concentrated antifreeze for every 100 feet of 1.5″ pipe. For larger diameter pipes or long runs, you may need significantly more.
- Start from the top: For exposed above-ground lines, pour antifreeze directly into the pipes through the return fitting until it starts flowing out the other side. If needed, use a funnel to carefully direct the antifreeze into the opening without spilling.
- Move toward the bottom: For buried pool plumbing, you’ll want to connect a short section of a hose to the return fitting so you can route the antifreeze exactly where it needs to go. Add enough until you see it discharge from the pool’s return jets or coming up through backwash ports.
- Go slow, then blow: Add the antifreeze slowly so it can more easily flow through the system. When you’re done, use compressed air to blow out any remaining puddles of antifreeze from the lines.
Always follow the antifreeze manufacturer’s instructions for proper dosage rates and application procedures. Never exceed the recommended dilution ratio.
How to Save Money on Pool Antifreeze
The best way to save money on antifreeze is to use less of it at once. Follow these tips to make it last longer:
- Add antifreeze primarily to places that tend to hold water, like the bottom of pipes or low spots where drainage is poor.
- Buy antifreeze in bulk quantities to get a discounted per-gallon price. Storing excess antifreeze is fine as long as you tightly seal the containers.
- If you have a pool cover, consider leaving more water in the pool and lines over winter. The cover helps prevent surface freezing, reducing risk.
- Only treat the most vulnerable pipes and components. If some plumbing runs below the local frost line, it may not require antifreeze.
- Reuse antifreeze for several seasons since propylene glycol does not degrade over time — simply top it off each fall.
- Shop end-of-season sales in early fall when retailers are trying to clear out inventory of seasonal products.
Improving Drainage to Minimize Antifreeze Use
Another great way to save money on antifreeze is to improve your pool plumbing’s drainage. Any puddles not displaced with antifreeze are prone to freezing, so you should minimize any low spots where water can collect.
Check areas near the valves, elbows, pipe joints, and equipment connections for low spots. Reroute or slope the plumbing as needed, and blow out pockets of standing water with compressed air.
You can also install drains at the low end of plumbing runs. This helps remove the bulk of the water before you add antifreeze. Drainage caps with a stop plus help control water flow when draining lines, while still allowing access in the future.
Storing Antifreeze Safely
Take steps to store pool antifreeze properly:
- Avoid direct sun exposure and extreme heat, which can degrade the antifreeze over time.
- Keep it tightly sealed and label the contents clearly.
- Never reuse food, beverage, or other household containers to store chemicals.
- Store in a locked area away from children and pets.
Having a dedicated chemical storage shed keeps all your pool chemicals safe and organized in one place. Make sure the storage area has proper ventilation.
Never mix different pool chemicals together or store them near other hazardous materials. Pool antifreeze is generally non-reactive, but it’s still smart to store it separately just to be safe.
Disposing of Antifreeze Properly
Many areas prohibit dumping diluted pool antifreeze down the sanitary sewer system, since propylene glycol can encourage bacterial growth at water treatment plants. Check with your local government to confirm its policy on the matter.
Alternatively, dispose of old antifreeze through a hazardous waste collection program. Some retailers accept antifreeze and other chemicals for proper disposal as a community service.
Never dump pool antifreeze down a storm drain or into a septic system. This can pollute groundwater and harm wildlife, and it’s potentially illegal.
FAQs About Pool Line Antifreeze
Only pipes and components that will hold water after draining need antifreeze. Sections that run below the local frost line can be drained and left empty over winter.
You only need to replace all the antifreeze every few years. Just top it off each fall as needed. Test kits are available to check freeze protection levels.
Antifreeze concentration and protection levels vary. A typical commercial product protects down to around -50°F. Higher concentrations safeguard plumbing at -100°F or lower.
No. Mineral spirits have a high freezing point and won’t protect pipes from bursting. Use only propylene-glycol-based antifreeze.
Maybe, so long as the pipes run below the frost line. You must treat any above-ground plumbing with antifreeze if it holds standing water.
