Why Is My AC Leaking Water Inside the House?

Finding water pooling near your indoor AC unit or damp spots spreading across the floor is one of those moments that stops you in your tracks. It doesn’t look right, and it’s hard to know right away whether it’s a minor issue or something that needs immediate attention.

The good news is that an AC leaking water inside the house is one of the more common problems homeowners across the North Shore and Northeast Massachusetts deal with, and in most cases, it points to one of a handful of known causes.

Common Reasons Your AC Is Leaking Water Inside

There are a few factors that can disrupt your AC drain, and some are more common than others. These are the causes that come up most often on the North Shore and Northeast Massachusetts.

Clogged Drain Line

The drain line is the most common culprit, and it’s easy to see why. Over time, algae, dust, and debris build up inside the line and eventually completely block the flow of water, causing it to back up into the drain pan and overflow onto the floor. Signs that a clogged drain line is the issue include:

• Water pooling directly beneath or around the indoor unit
• A musty or stale smell coming from the vents
• The unit shuts off on its own due to a built-in safety float switch

Clearing a drain line is straightforward for a technician and is typically checked during a routine AC maintenance visit.

Frozen Evaporator Coil

Ice forming on the evaporator coil is another frequent cause of indoor water leaks. When airflow through your AC is restricted, the coil gets too cold, ice builds up, and when it eventually melts, the volume of water can easily overwhelm the drain pan. Watch for these signs:

• Warm air is blowing from the vents even though the unit is running
• Frost or ice visible on the indoor unit or refrigerant lines
• Water is leaking more heavily after the unit has been running for a while
• A hissing or bubbling sound near the unit

A frozen coil is usually caused by a dirty filter, low refrigerant, or a blocked vent, and needs to be addressed before it causes more damage.

Dirty Air Filter

A clogged filter is one of the simplest causes of a water leak and also one of the most overlooked. When a filter gets too dirty, it blocks the airflow your AC needs to run properly. That restricted airflow causes the evaporator coil to freeze, and when the ice melts, the water overflows the drain pan. Most homeowners don’t realize how quickly a filter can get dirty during heavy summer use. A few things to check:

• Hold the filter up to a light source. If you can’t see light through it, it needs to be replaced.
• Check whether airflow from the vents feels weaker than usual.
• Look at how long the unit is running to reach the set temperature. Longer run times often point to restricted airflow.

Replacing or cleaning the filter regularly is one of the simplest ways to keep water where it belongs.

Damaged or Rusted Drain Pan

In older units, the drain pan that sits beneath the evaporator coil can crack, rust through, or warp over time. Once it can no longer hold water properly, leaking becomes inevitable regardless of whether the drain line is clear. Unlike the other causes on this list, a damaged pan won’t respond to cleaning or filter changes. 

If the leak keeps coming back after other fixes have been tried, the pan itself is worth inspecting. A technician can confirm whether it needs to be replaced and check for any other contributing issues at the same time.

When To Call a Pro

Some AC leaks are easy to trace, but others need a trained eye to diagnose correctly. Super Service Today serves homeowners across the North Shore and Greater Boston and can typically get to you the same day for a leak. It’s worth making that call if any of the following apply:

• You can’t identify where the water is coming from
• The leak keeps coming back after basic fixes
• You suspect a refrigerant issue based on warm air or hissing sounds
• Water has already reached the walls, flooring, or ceiling materials
• The unit keeps shutting itself off

AC repair from a licensed technician is the right move when the source isn’t obvious or when water has already started causing damage.

Why Homeowners on the North Shore Choose Super Service Today

Water leaking from an AC unit deserves a real diagnosis, not a quick patch that leaves the underlying cause unaddressed.

• Same-day service: When something needs attention right away, we can typically get to you the same day, so the problem doesn’t sit and spread.
• Flat-rate upfront pricing: You’ll know exactly what the repair costs before any work begins, with no surprises afterward.
• Diagnostics waived with repair: If we identify the cause of the leak and you proceed with the repair, the diagnostic fee is waived.
• Licensed, bonded, and insured technicians: Every technician who comes to your home is fully credentialed and follows a documented process from the first look to the final check.

Super Service Today has been serving homeowners across the North Shore and Greater Boston since 2010 as a locally owned, family-operated company.

Schedule AC Repair on the North Shore

A water leak from your AC might start as a small puddle, but if left unaddressed, it can lead to mold growth, damaged flooring, and a repair bill much larger than it needs to be. Getting it looked at early is almost always the cheaper and less stressful path forward.

Super Service Today serves homeowners across the North Shore, Greater Boston, and Northeast Massachusetts. Call (781) 519-9921 or schedule service online to get it sorted before it gets worse.

FAQs

Is it normal for an AC to drip a little water?

A small amount of condensation around the outdoor unit is normal, but water dripping or pooling near the indoor unit is not. If you’re seeing moisture inside the house, it’s worth having it checked out because even a slow drip can cause damage over time if the source isn’t addressed.

Can I fix an AC water leak myself?

Some causes, like a dirty air filter or a mildly clogged drain line, are things a handy homeowner can address. But if the leak persists, the source isn’t obvious, or you suspect a refrigerant issue, it’s best to call a licensed technician. Refrigerant requires certified handling and isn’t something to attempt on your own.

How much does it cost to fix an AC that is leaking water?

The cost depends entirely on the cause. Clearing a clogged drain line is typically one of the less expensive repairs, while replacing a drain pan or addressing a refrigerant issue will cost more. The best way to get an accurate number is to have a technician diagnose the problem first so you know exactly what you’re dealing with.