Water damage from an HVAC system? You read that right. Home and business owners often do not realize that a Heating, Ventilation & Air Conditioning (HVAC) system that isn’t draining properly can cause expensive water damage to your home or business. That isn’t the only cause of water damage, of course, other important ones include plumbing, roof, and floor leaks. The following is a look at all of them.

Why damage from HVAC?

The water from your HVAC system has to go somewhere, but unlike a sink with a drain that is plumbed to a sewer or septic system, the water from the HVAC system in your building or residence doesn’t flow directly into a city sewer, but merely drains out of the building and onto the ground. Consider: Your HVAC system generates up to one gallon of water in each AC cycle – lasting roughly 15 minutes – water damage can result mighty quickly if the system is not draining properly!

Second, let’s say it is your heating system that is on and not your AC. There may not be nearly as much water per se, but a plugged system still means plenty of gunk is forming in the drain pipe and drain pan that will back up and pose potentially expensive problems. (Extensive mold being but one possibility.)

Several caveats worth noting. Even if you rent or lease your business space, you are often still liable for the damage caused from a faulty system. And that can easily cost hundreds of dollars or worse.

Here are some recommendations for avoiding costly water damage from a faulty HVAC system:

* The HVAC unit evaporator coil and drain pan should be elevated when installed to insure proper drainage.

* The drain line should be 3/4 PVC pipe (schedule 40 recommended as opposed to thinner schedule 20 pipe used under a kitchen sink) with a minimum drop of 1/8″ per foot or 1 inch every 8 feet to ensure proper downhill flow for drainage.

* Drain line support should be installed every 4 feet to insure that drain line runs straight without sagging, which can create a lull that can trap water causing drainage problems.

* Consider running a cleaner in the drain line on a regular basis to break up gunk or other pollutants that might otherwise form. Some systems can even be set up for a cleaner to run automatically at regular intervals.

* A condensation water trap should be installed at the beginning of the drain line run as it leaves the HVAC unit or at the end of the drain line run where water terminates from the system.

The following are additional sources of water damage that a tenant may be responsible to repair:

* Plumbing leaks: hot water heaters, toilets, and sinks are obvious fixtures at risk for a water leak. Many property owners and tenants do not realize that there are a number of more subtle sources of leaks. Drain line problems can cause sinks and toilets to malfunction, and old drain lines often corrode, leak, collapse or become infiltrated by roots. Pipes punctured by drywall nails or screws during construction and renovation are a ticking time bomb. These “nail in pipe” problems may NOT leak water for days or even years after the problem is created, but when they do, look out!

* Roof leaks not only occur in the top tenant (closest to roof), but even in the ceilings of ground floor tenants. Water can follow beams, posts, columns and walls becoming evident only when the ground floor space ceiling causes the water to pool and stain the ceiling. Sometimes, a roof leak even presents itself as water on the floor of the tenant space.

* While many floor leaks are actually plumbing leaks below the slab or floor, just as many are a result of poor drainage outside the building that causes water to pool below the slab or floor. As noted earlier, that water has to flow somewhere!


It’s worth noting that many insurance policies consider rising drainage water to be “flood damage” and will only cover such damage if the business owner has flood insurance or a flood rider.

Clearly, whether you’re a homeowner or owner of a small commercial business, ignore water drainage and potential leaks at your own peril!