Water Leaks – Pipe on Side of House

Water Leaking from a Pipe on Side of House – What Is It?

There’s water leaking from a pipe on the side of my house. Should, I call a plumber or an air conditioning company?

As the owner of a busy air conditioning company in Mesa / Phoenix, AZ., I hear this question asked a lot. If you see water leaking from a pipe outside your house, the first thing to do is identify where the pipe is and what material it’s made from. This will give you an indication if the water leak is normal, or means you need service – and from whom?

AC Drain Lines and Water Heater PRV Lines

The two most common drain pipes that most people have on the side of their house are air conditioner condensate lines (AC drain line) and water heater pressure relief valve lines (PRV drain line). Let’s talk about each separately as this is the quickest way to know if your water leak is normal or something urgent.



Water Leaking from AC Drain on the Side of the House

The most common water leak from a pipe outside your home is going to be from your central air conditioner’s condensate drain line. To see it from one pipe is completely normal and means your drain line is not clogged and operating normally. The other means your “primary” drain line is clogged, and you should schedule AC service as soon as possible.


Horizontal AC Air Handlers  – AC air handler in your attic

Your central air conditioner is typically made up of at least two pieces of equipment. The condenser unit (this is the machine in your yard with the compressor and outdoor aka condenser fan inside), and the air handler aka indoor fan coil.

Many people don’t even know the air handler is part of the air conditioning “system” and think the unit in their attic is just the furnace or heating system. Regardless if you have gas heating from a furnace, or heat pump heating from an air handler, you have an evap. coil inside your home that is connected to the outdoor unit. This coil is where condensate (moisture removed from inside your home) is collected and then drained via the condensate drain line to the side (or elsewhere) of your house.

Air conditioner drain lines are made from PVC (white plastic). Size-wise this pipe or PVC fitting (a 90°angle called an elbow) is about as thick around as the circle created when you put your index finger and thumb together (3/4”).

Horizontal air handlers should have two drain lines which terminate on the side or back of your house. Most often these two terminations (where the pipe comes out of the outside wall) will be in line with each other. One will be down low near your foundation, the other up high near the attic. The low one is the AC unit’s “primary” drain line, the one up near the attic is the air conditioners “secondary” or “emergency” drain line.


IMPORTANT: If the AC drain line up high near the attic is leaking water, call your local AC company for service immediately. The emergency drain line is called that for a reason!


The pipe down low is the primary or main condensate line from your air conditioner. Seeing water dripping or trickling from this line is normal operation, and you can probably relax – but read the rest of this article before you do.

The emergency drain line is connected to a shallow pan installed below your air handler. This pan is known as the overflow drain pan, secondary pan, or emergency drain pan. This pan is designed to catch water when your primary drain line is clogged in the hopes to protect your attic, ceiling and personal belongings – but is only meant to provide temporary protection.

If you see water coming out of a pipe on the side or rear of your home up high, it means your main condensate line is clogged and you need to call for AC service right away. It is purposely installed high up, so you notice the water dripping sooner than later.


What Do Rust Stains on Outside Wall from Your AC Drain Line Mean?

If you notice rust stains running down the wall on the exterior of your home below the emergency drain line, you should have it inspected.

Sometimes, this an indication that water has been collecting in air conditioners emergency drain pan for a long time. The long-term effect causes the pan to rust and then slowly drip rusty water down the side wall. Even if you don’t see water there presently, it’s worth looking at because if the pan rusts through it can leak inside your home. Or worse, not show up immediately and begin to grow mold.


When is it Normal to See Water Dripping from the PVC Pipe on the Side of Your Home?

In most cases you should expect to see water dripping out of your AC’s primary condensate drain line (PVC elbow near the home’s foundation). This is especially true when the humidity in your home is higher, like during monsoon in Arizona.

NOTE: If you see rust stains in this area, it’s a sign that your indoor coil or primary drain pan are rusting, and you should have it inspected. Although it’s not unusual for us HVAC technicians to see rusty coils and pans on older equipment, it’s worth the cost of an inspection to make sure everything is okay.


Vertical AC Air Handlers – air handler in garage, hall closet, or mechanical room

Vertical air handlers rarely have any form of secondary pan as the application does not usually allow for one. In this case, there will be no secondary drain pipe up high. The low pipe acts in the same way it would from a unit in the attic. 


Water Leaking from a Copper Pipe on the Side of the House

Most likely water leaking from a copper pipe or elbow shaped fitting down low is an indication that the PRV (pressure relief valve) on your water heater is leaking. This device is intended to keep your water heaters tank from building up pressure and literally blowing up.
By code this valve must be hooked up to a rigid copper drain pipe and run to the exterior of the home. If water is rushing out of this pipe, you should turn off the water valve located near the top of your water heater and call your local plumber for repair.

If water is slowly dripping out of this pipe, you can try very lightly tapping on the top of the valve with a small hammer or wrench which may re-seat the valve. You still want to keep an eye on it however and make sure the dripping stops. If you are not mechanically inclined, you are probably better off hiring someone who is.



How Often Should AC Drain Lines be Checked or Flushed Out?

Most experts and manufacturers agree you should have your AC unit inspected twice a year. However, you only need to inspect and flush your condensate line before the cooling season. Personally, I blow out my own primary condensate line with compressed nitrogen every spring and then flush it with water to make sure it’s completely clear.

You’d be surprised (and sometimes grossed out) when you see what comes out of these lines. Besides the spiders, mud wasps and other creepy-crawly’s that like to hide and nest in these pipes there’s the “sludge”. Remember this is not like a water pipe that has higher pressure water moving through it keeping it clear. It’s slowly dripping condensate that mixes with the rust and dirt that collects on your indoor coil and the sediment that collects in the primary pan.


Save up to $100 on Your AC Repair Service

If it’s been more than a year since you last had your air conditioner’s drain line flushed out, contact us today and take advantage of our current promotions!