How Much Water Evaporates From A Pool In Arizona?

infinity edge pool in hills of arizona with cactus and shrubs surrounding

One of the options you’ll be faced with when buying a new pool is whether or not you want an automatic water leveler.  You may be thinking you don’t need it. Instead, you’ll simply top off the pool with the hose here and there. However, what if you live in the southwest?  How much water evaporates from a pool in Arizona?  You might be surprised to find out how much water can simply disappear and how often you’ll need to be there with the hose to top it off.

My Arizona Background

In this article we’ll explain how much water evaporates from pools in Arizona. We’ll also explain why this happens and suggest some ways to deal with this unavoidable part of Arizona pool life. I’ve spent nearly a decade as a pool designer in Arizona. During that time I dealt with this evaporation question and problem a lot. In addition to working in the pool industry, I lived and owned a pool in Arizona, more specifically Queen Creek and Mesa. I say this to explain that I have plenty of experience with this issue and want to offer my knowledge to you.

How Much Water Evaporates From A Pool In Arizona?

First, you can start with the baseline. The accepted jargon of the pool and spa industry is that pools lose 1/4” per day in evaporation.  Ask anyone in Arizona and they’ll laugh at that number or say ‘yeah, maybe in winter’.  The reality is you’re losing a minimum of 1/2” per day in the Arizona heat.  We say minimum because if you have a feature like a waterfall, an infinity edge, or an aerator, that number goes even higher.

Why Does So Much Evaporation Occur In Arizona Pools?

Aside from just heat, Arizona is common for having more water features and different terrain than other parts of the country. We’ll now explain a bit further about some high evaporation causes.

Waterfalls Affect On Evaporation

A running waterfall exposes more water surface area to the dry air by the nature of how a waterfall works.  The water gurgles and flows in a thin sheet, spraying and rushing as it goes.  By exposing more of the water surface area to the air, more water evaporates. Therefore, the temperature of the remaining water goes down slightly.  

That’s right, evaporation is key to losing heat from the swimming pool. This is why in Arizona there are features which actually accelerate evaporation, like aerators.  Aerators spray water above the water line in a fine stream over the surface of the pool, like a sprinkler head.  These increase evaporation of the pool water, which helps cool down the water slightly.

Automatic Covers For Evaporation Prevention

As you probably know, Arizona is very different in the northern and southern parts of the state. Additionally, if you are in a northern climate, or northern Arizona for that matter, you may consider using an automatic cover to prevent evaporation, thus reducing heat loss from the pool.  Automatic covers are also common in the lower elevations of Arizona. Although it’s often good idea to pair them with a heat pump with a chiller option. The reason being that the pool can get too warm in summer when it’s always covered.

Infinity Edge Pools Affect On Evaporation

Infinity edge pools, like waterfalls, have a tendency to cause an increase in evaporation as well.  The water running over the weir and down to the surge basin causes the same effect of more water surface area coming into contact with the dry air, increasing evaporation.  You should also expect more evaporation if if you live in an area with higher winds. Properties on the top of a mountain or edge of a valley will notice a higher evaporation rate. The ideal pool location albeit less scenic is in a backyard with walls surrounding it.

backyard showing how much water evaporates from a pool in arizona via water features and a dry distant golf course behind the home

How To Measure How Much Water Evaporates From A Pool In Arizona

One aspect of pool water chemistry to keep an eye on in Arizona is the total dissolved solids level in your pool.  In Arizona in particular you are often refilling the pool with very hard water. The water that evaporates into the air is pure distilled water, leaving behind all the calcium and solids.  This means your pool water will become harder and harder over time, leading to scale buildup at the water line of the pool, and throughout the pool interior. If you notice your total dissolved solids reaching above 2,000 PPM, it is time to drain some water out of the pool.  

How Much Water Evaporates From A Pool In Arizona Summary

When answering the question how much water evaporates from a pool in Arizona, you can see there are more than just the obvious answer to keep in mind. Without doing research, homeowners often underestimate the amount of evaporation that takes place. The amount of evaporation in Arizona pools is dramatically higher than other parts of the country. Along with the amount, people also misunderstand why the evaporation occurs. Water evaporation actually reduces the temperature of your pool water.

If you have water features, your pool will have even more evaporation. One important thing to keep an eye on is your total dissolved solids level. It’s not uncommon for evaporation to cause high calcium levels and scale build up. Arizona is a unique climate to live in. We know it especially well since we lived there for over 5 years. Its desert qualities can make every aspect of the backyard a challenge, from choosing the right patio furniture to maintaining a healthy pool.