Large buildings contain some surprising sources of water. In the past, they were considered a nuisance and dumped out. Now, these waters are gaining value and being reused. 

In large buildings, the heating, ventilation, and air conditioning  (HVAC) system produces water as a byproduct. It is called air conditioning condensate water.

You can observe condensation in action by putting out a glass of ice water on a hot day. The cold surface of the glass draws moisture out of the air, causing drops of water to condense on the outside of the glass. Air conditioning systems in large buildings can condense millions of gallons of water each year.

Condensate Water

Condensate water is pure water molecules. However, this water can pick up pollutants as it runs over the surface of the air conditioning unit. Because of this, condensate water is considered non-potable, or not safe to drink.

Most buildings that produce condensate water also need a large supply of non-potable water to operate their cooling towers, which is an easy place to reuse the condensate water. Condensate water can also be used for toilets, irrigation, and ornamental fountains or ponds.

Rice University in Houston, Texas, saves over 14 million gallons a year by recycling the condensate water from just one air conditioning unit. The water is captured and directed back to the central plant’s cooling towers.

Foundation Drainage Water

Some buildings tap into another source of water hiding underground.

The foundations of large buildings are dug deep into the ground and can reach groundwater in some locations. This water must be pumped out to avoid problems in the building, like flooding in the basement. In the past, this foundation drainage water was dumped, but now it can be reused. 

A medical center in Los Angeles saves 80,000 gallons a day by collecting foundation drainage water. That’s like saving 2,700 bathtubs full of water every day! After collecting the water, it is cleaned and used in the building’s cooling towers.  

How Can You Help?  

Many homes do not have mechanical water or foundation drainage water. However, if you have an air conditioning (AC) system you may have a small supply. Look for water dripping off the AC unit. Can you connect a tube from the AC unit to a planter box or collection barrel?  

It’s important to keep in mind that some sources of water are not suitable for reuse, so always check with your adults and do research if you want to reuse water at your house. 

Are there large buildings with air conditioning systems in your town? You could write to them and suggest they look into mechanical water reuse. 

Condensate water and foundation drainage water don’t have to be a problem. Reusing them is one piece of the larger solution to protect our valuable water supplies and save water!