Topping off your pool is an essential part of pool maintenance. As water evaporates from your pool over time, the water level drops. Topping off your pool replaces the water lost to evaporation and keeps your pool at the proper water level. But how often do you really need to top this off? There are a few factors to consider when deciding how frequently your pool needs topping off.
How Much Water Evaporates from Your Pool?
The rate at which water evaporates from your pool depends on several variables:
- Air temperature – Warmer air causes faster evaporation
- Humidity – More humid environments see less evaporation
- Wind – Breezy conditions increase evaporation
- Pool size – Larger pools have more surface area for evaporation
- Pool shape – Freeform and curved pools evaporate more than rectangular pools
- Sun exposure – More sun exposure means more evaporation
As a general guideline, most pools lose between 1⁄4 and 1⁄2 inch of water per week to evaporation. However, this can vary significantly depending on your local climate conditions. Evaporation will be faster in hot, dry, windy environments and slower in cool, humid conditions.
Monitoring your pool’s water level is the best way to determine your pool’s specific evaporation rate. Lowering of 1⁄4 to 1⁄2 inch per week is normal and indicates it’s time to add more water. Larger drops likely signify an abnormal leak that requires repair.
Ideal Pool Water Level
Maintaining proper water levels is important for pool operation and efficiency. When water levels drop due to evaporation, it negatively impacts several areas:
- Pump efficiency – Pump must work harder with less water to circulate
- Skimmer function – Low water can prevent skimmers from working correctly
- Pool circulation – Improper water levels disrupt normal flow
- Chemical balance – Chemical concentration and pH become erratic
- Pool surface – Low water exposes more of the pool surface to air causing fading
- Pool equipment – Equipment like heaters and cleaners function best at proper levels
For proper operation, the pool’s water level should be midpoint on the tile or about 1⁄2 inch below the coping/decking. This optimal level allows skimmers, returns, and other equipment to work as designed.
When to Top Off Your Pool
Most pools should be topped off on a weekly basis during the swim season. To determine your pool’s needs:
- Check water levels weekly
- Add water if the level drops 1⁄4 to 1⁄2 inch below ideal level
- Top off using a hose on low flow directly into the pool—not into skimmer
- Run the filter pump while adding water to evenly distribute
During hot summer months or windy conditions, checking twice weekly may be necessary to maintain proper levels. In cooler climates and indoor pools, less frequent topping off may be needed.
It’s important to monitor and top off on a regular basis. Drastic changes in water level are not ideal for your pool system. Allowing levels to drop too low before topping off can be damaging.
How Much Water to Add
When topping off your pool, you only need to add enough fresh water to raise levels back to normal. For most pools:
- Adding 1⁄4 to 1⁄2 inch of water increases level by approximately 1 inch
- An average 20,000 gallon pool needs 150 to 300 gallons of water to raise level 1 inch
- Use pool depth, shape and gallon amount to estimate how much water you need
Small, frequent additions of fresh water are preferred over large occasional top-offs. Drastically altering the water volume through large water changes can negatively impact chemical balance.
Tips for Topping Off Your Pool
Follow these tips for topping off you pool properly:
- Check water levels weekly and top off as needed
- Add water directly to pool, not skimmer, while filter pump runs
- Use a hose on low flow to prevent pool surface erosion
- Add fresh water slowly to allow gradual mixing
- Avoid drastic water level changes; small weekly increments are best
- Always add water to proper midpoint level—not too high or low
- Consider covers, wind breaks, and water features to reduce evaporation
Proper water levels are crucial for pool operation. Just 1⁄4 inch of water loss per week can add up quickly. Stay vigilant in monitoring and topping off your pool. Making this task part of your regular maintenance routine is key for both water balance and system efficiency.
Using Pool Covers to Reduce Evaporation
Using a pool cover is an excellent way to minimize evaporative water loss between swimming seasons. Pool covers create a protective barrier preventing the water’s exposure to sun, wind, and hot air. Studies show pool covers can reduce 70-90% of normal evaporation. This greatly minimizes the amount of topping off needed.
There are a few types of covers ideal for reducing evaporation:
Solar Pool Covers
Solar covers, also called bubble covers, are lightweight polyethylene blankets that float on the pool’s surface. The bubbles trap heat while limiting evaporation. Solar pool covers also have the added benefit of raising pool water temperature. They are inexpensive, easy to install, and work well at minimizing water loss.
Safety Pool Covers
Safety covers completely seal off the entire pool surface. They are anchored around the perimeter and can support weight, providing protection against unintentional falls into the pool. The solid top blocks sun and prevents wind exposure. Safety covers are the most evaporative pool covers, typically reducing water loss by 90-95%.
Automatic/Mechanical Pool Covers
These covers use motorized systems to mechanically cover and uncover the pool. Made from vinyl material, they fully seal the pool with the turn of a key. Automatic covers offer the ultimate in convenience while completely eliminating evaporation when covered. Installation is more complex than other cover types.
Tips for Using Pool Covers:
- Completely cover the pool – Overlap slightly and anchor firmly
- Use when pool is closed 3+ days or between seasons
- Select cover compatible with pool type, climate and safety factors
- Consider automatic covers for ultimate evaporation prevention
- Remove debris before covering and uncover fully before use
- Allow condensation to dry before rolling cover for storage
Pool covers are a smart investment giving you peace of mind against water loss. Just be sure to completely uncover the pool before swimming as covers are not intended for walking on.
Preventing Evaporation with Wind Breaks
Wind accelerates evaporation by disturbing the pool’s surface and carrying away humid air. Creating barriers around your pool is an effective way to minimize wind. Solid fences, hedges and privacy panels are ideal for blocking wind.
Evergreen trees and shrubs are great windbreaks as they don’t lose leaves seasonally. Some ideal options include:
- Arborvitae – Dense green foliage grows tall, providing excellent wind screening. Many varieties available.
- Juniper – Soft looking needles and ability to withstand shearing make junipers ideal natural fences.
- Spruce – A classic privacy tree, spruce grows over 50 feet tall and hold branches low to the ground.
- Cypress – Handsome conical form with feathery leaves that blocks wind. Does well in wet soil.
- Privet – A popular hedge plant that tolerates frequent pruning into dense buffers.
Trees and shrubs can dramatically slow winds near the pool. Place them to block prevailing wind direction. Allow ample space between plants and pool for mature size. Hardy, dense evergreens work best to deter moisture-robbing wind.
Using Water Features to Add Moisture
Water features add soothing sights and sounds while boosting humidity. The mist and spray introduced into the air minimizes evaporation from your pool. Features like waterfalls, fountains, cascade water walls and sheetfalls work well.
Benefits of Adding Water Features:
- Increases humidity above pool surface
- Blocks wind when designed appropriately
- Adds relaxing ambiance
- Masks background noise pollution
- Provides added recreation
When planning water features, consider:
- Placement near prevailing winds to act as barrier
- Siting that prevents water spraying directly into pool
- Pumps sized appropriately for feature flow rate needs
- Extra plumbing, electrical and drainage requirements
- Added maintenance of pumps, nozzles, water quality, etc.
The cooling mists create a microclimate around your pool, keeping the area more humid and reducing evaporation. Just be sure water sprays away from pool area to prevent unnecessary extra water loss.
Conclusion
Maintaining proper water levels through regular topping off is crucial for pool health and efficiency. Monitor pool levels weekly, adding small amounts of makeup water as needed. Using pool covers, wind barriers and water features also help tremendously by preventing evaporation between swim seasons. With routine attention, you can ensure your pool’s water level stays right where it should be.
