Swimming pools have become a regular fixture in the backyards of many modern homes. They add to the aesthetic appeal of a property and make it easier for homeowners to enjoy the many benefits of swimming. Pool overflow drains are important for keeping the water levels in the pool in check, but where does the overflow go?
A pool overflow can go into the drainage system, a reservoir within the property, or a tank for processing and reuse. Some pool designers also set up the overflow to act as a quasi-irrigation system for a home’s garden or lawns. The overflow destination is typically discussed during design.
Knowing the destination of your pool overflow can help you avert problems in the future. The rest of the article will cover all the possible options.

Possible Destinations for a Pool Overflow Drain
If you have a pool overflow drain, the water collected goes to any of the following destinations:
Drainage System
The design of your overflow drain may channel water into your drainage system, which keeps excess water away from the surface. However, it’s not always the most efficient. If you live in an area where storms are commonplace, excess water can cause your septic tanks to fill up faster than normal.
Garden Drainage Pits
The pool overflow can also go to drainage pits constructed to hold excess water in the garden. The pipes from the drain are hidden away from sight and channeled into the drainage pit—which is typically up to 3 ft (0.91 m) deep and wide.
The design of the pit ensures it is deep enough to hold chlorinated water without harming the plant life around it.
Filtration Tanks
If your swimming pool is one of those designed with a filtration tank that can hold and recycle excess water, the pool overflow will go to the tank. The tank’s filtration system will then process the water to get rid of debris and bacteria before it is pumped back into the pool when necessary.
This elaborate system is efficient at keeping your swimming pool from overflowing, but it typically has to be installed during the construction of a pool. Some contractors can install such a system for an existing pool, but it will cost a significant sum.
Yard Runoffs
Sometimes there’s no elaborate system draining your pool overflow. A simple pipe connected to the pool drain and channeled to a corner of your yard can do the job.
If there are any pipes around your property with water flowing out after your pool overflows, that’s the destination of the pool overflow. Ensure it’s channeled into a corner of the yard where it won’t be a problem for your landscaping or leave neighbors unhappy.
Rainwater Collection Barrels and Tank Systems
Some swimming pool systems may feature pool overflow systems channeled to rainwater collection barrels or tank systems within the property. You’re likely to see this design if the rainwater tank is big enough and there’s a filtering and pumping system in place.
Street Gutters
The piping for swimming pool overflows can take the water into street gutters. The water escapes into the city’s drainage system and down out into larger water bodies.
If you live very close to any city drainage structure, the contractors may have channeled the pool overflow into it.
The above are some of the likely destinations of swimming pool overflow. If you’re still unsure which one applies to you, locate your swimming pool plan. You should have a copy of this if you paid for the design and construction.
If you don’t have the plan, you can call the contractors and ask them.
What Are the Causes of Pool Overflow?
The causes of pool overflow happen when too much water is allowed in, which typically happens accidentally during refills. However, storms and heavy rainfall can also cause pools to overflow.
Water displacement from when swimmers dive into the pool is usually not enough to cause overflow as long as the water in the pool is at the optimum level.
Why Is a Pool Overflow Drain Important?
A swimming pool overflow drain is important because it ensures the water inside the pool is at the optimum level. Maintaining the right level of water is important to ensure a balance in the pool chemistry. The drain also reduces the risk of flooding nearby areas.
Let’s take a closer look at these benefits of a pool overflow drain.
Maintaining Pool Chemistry
Swimming pools need a chemical balance for the following reasons:
- Ensure an appropriate pH level.
- Keep bacteria and fungi away.
- Ensure a clear color of the water.
- Protect swimmers from harmful toxins.
If the pool overflows and it’s not drained away quickly, the chemicals in the pool can get diluted, disrupting this balance.
If your pool overflows and the situation is not quickly stopped, you may have to spend up to a week rebalancing the pool’s chemistry. The rebalancing process will start with shocking the pool with chlorine and then testing the pH with a pool test kit.
The optimum pH range for a swimming pool is 7.2-8.0.
Above 8.0, you’ll get scaling and cloudy water, and below 7.0, swimmers may experience irritation in the eyes and mucous membranes after swimming.
Preventing Flooding
If your swimming pool overflows heavily, the surrounding pool area and landscape will be flooded. If your patio area is paved and has good drainage, the flooding likely won’t be too much of a problem, as the excess water will evaporate or disappear into the soil quickly.
If the pool area doesn’t have proper drainage, you may face serious flooding problems. This is especially true if the construction is such that the water can get into your home or the garage.
Your landscaping may also be affected if the plants absorb a lot of chlorinated water.
A pool overflow drain prevents this from happening because the excess water will be channeled away from the pool and into the right receptacles. The drain might be overwhelmed during a weather event, but it will function effectively at other times.
How To Prevent Swimming Pool Overflowing
Here are a few things you can do to keep your swimming pool from overflowing:
Exercise Caution When Filling the Pool
When it’s time to add water to the pool or refill it, you need to pay attention to what you’re doing.
Don’t leave the water source running overnight or when you’re not close by. Keep an eye on the water level so you can turn off the water source at the right time.
Some automated systems can pump water and stop at a predetermined level without interference, but most residential swimming pools don’t come with such installations. You have to monitor the water levels manually.
Install Overflow Drain or Clean Existing Ones
If you have an overflow drain that doesn’t work optimally anymore, clean it to allow a free flow of water. You may need plumbing tools to reach into pipes and unclog them. Rent what you need to get the job done, or pay a professional if necessary.
Where no overflow drains are available, you have to create one as soon as possible. For overflow drains that won’t require manual intervention to get rid of excess water from the pool, you need to consult any qualified swimming pool contractors around you.
Alternative options are manually constructed overflow drain systems that will take water into a reservoir. Let’s now look at two of these systems.
Drainage Pit
You can dig a drainage pit to hold the water in your garden, as they can hold large volumes of water and can be completed in a couple of days.
Keep in mind that the pit should be above the groundwater level. The dimensions are usually 3 ft (0.91 m) for both width and depth. However, you can go with smaller dimensions if necessary.
Once the pit is dug, don’t forget to lace the bottom with some polished stones. Keep the site of the construction at least two meters away from your home’s foundation wall.
Before you start digging, don’t forget to look at local laws to see if it’s allowed.
Water Pump
This option is popular because it helps you avoid any digging. With a hose and small pump, you can pump away water from the pool when necessary. The excess water can go out to the streets or into a tank.
Again, you should check with your local authorities to ensure you’re not breaking any regulations by channeling wastewater into street gutters from your home.
Final Words
Pool overflow will typically go into your home’s drainage system or directly out into the city’s systems. The excess water can be recycled in a tank and reused for high-end pool constructions when it’s time to top up the pool again.
When unsure where your pool overflow ends up, talk to the original contractors for the pool project. In a rental home, you can talk to the landlord. If they didn’t make any provisions for overflow drainage, you can choose any of the options that appeal to you the most to keep your pool from overflowing and flooding your landscape.