A nice outdoor pond can be a wonderful addition to any backyard landscaping project, but it’s not as simple as digging a hole and pouring some water in. Depending on what you are planning to do with your pond, it may require nearly as much planning and care as an in-ground pool. This may require you to install a drain to help manage debris.
In general, outdoor ponds do not require a drain to function properly. That being said, they can make maintenance significantly easier if installed correctly, as their main benefit is to remove organic waste from fish as well as keeping the water from sitting still and stagnating.
Drains are one of those things that probably make you think “what’s the harm?” Sometimes, there isn’t any harm in putting in a drain, and in cases where there’s a big pond or you have a significant issue with debris, it might help. If you keep fish though (especially small fish), or in some other circumstances, putting in a drain may cause more harm than good.
Does Your Pond Need a Drain?
There are a surprisingly wide variety of ponds out there, each intended for a different use. Here are just some of the wide variety of ponds that people get installed in their yard:
- Koi Pond
- Swimming Pond
- Garden Pond
- Wildlife Pond
- Farm Pond
Each of these types of ponds are used for different purposes, are different sizes, and have different recommendations for installing a drain. Generally speaking, however, drains don’t need to be installed to keep a pond healthy and functioning properly, but having a drain can make maintenance and cleaning significantly easier and, in some cases, remove the need for it.
In most cases, drains can provide some benefit to a pond, and in the case of larger ponds, it may lead to a better outcome and less cleaning. This should be cautioned with the fact that smaller fish can sometimes get sucked into a drain if you have them, or cutting a hole in a stock pond liner in order to facilitate installing a drain could lead to leakage issues.
There’s something to be said for installing the components of a drain while you’re installing the rest of the pond. A drain won’t cause any issues if it’s not actively being used, but having it installed at least gives you the option to use it in the future. You can always plug one side of it and continue cleaning your pond as normal until you decide you want to use it.
Purpose of a Drain
When you think about a pool drain, you think about the need to keep floating debris controlled and out of the pool, as well as a way to keep the water circulating. This is really the essence of a drain’s purpose. Standing water can become a breeding ground for insects, pests, bacteria, and vermin, and can lead to health concerns.
In addition, your pool or pond will accumulate a significant amount of debris on a daily basis, and you could spend hours every day trying to keep it clean. This debris can include dead bugs, leaves, sticks, or whatever else is floating around your yard.
In the case of a pool, these items could also damage your pool liner. In the case of a pond, especially those ponds where you’re keeping decorative fish, these items could endanger their health and well-being.
This is all not to say that drains are required for a pond. Rather, it is to say that drains do serve some benefit, but not necessarily that much if it’s a pond (unless it’s a swimming pond, but more on that later). In general, people are not going to be going in your pond so you don’t need to keep it as clean as a pool for health concerns.
Pros and Cons of Installing a Bottom Drain in a Pond
There are a number of pros and cons for installing bottom drains in a pond that can be summed up in the table below. Each of these arguments will be described in more detail below.
| Pros | Cons |
| Can help with water circulation | Can be expensive to install |
| Reduces the requirement for pond cleaning | Can cause leaks in stock pond liners |
| Reduces amount of waste in a pond | May get clogged regularly |
| Can help fish be healthier | Small fish can get caught in the drain and die |
Arguments for a Pond Drain
A pond drain can help with water circulation, especially in ponds without other mechanisms to keep water moving constantly. This helps keep water from stagnating as well as keeping it oxygenated to encourage plant and fish growth.
A pond drain may also reduce the requirement for cleaning. While it may experience problems with clogging, it can also help keep the amount of organic waste in a pond down, which can help keep fish healthy. Without a pond drain, there’s a significant chance that you’ll have to drain your pond water annually to remove organic waste.
Arguments Against a Pond Drain
One of the biggest arguments against having a bottom drain in a pond is the excessive cost installing one can incur. Not only do you have to dig a hole for the drain itself, but you’ll have to dig a spot for the plumbing that goes to the filter outside of the pond, which adds more components to have issues with. Clogs aren’t unusual in the discharge pipe either.
Many ponds are installed with stock liners that don’t come with a hole already cut in them for a drain at the bottom. Even a professional cutting a new hole for a drain is very likely to cause leaks, which could lead to issues with the ground around the pond in the future. It’s also a waste of water if you constantly have to refill your pond due to a leak at the bottom.
Filters and drains can often clog if there’s excessive debris, and this debris won’t necessarily cause issues for the pond if not cleaned out daily. Usually, professionally installed ponds will include built-in mechanisms for aeration and water circulation as well, which removes the need for a separate pond drain.
There is also the potential for small fish to get caught in the drain or the filter, which could harm or even kill them. This isn’t as big an issue for larger fish like koi fish, which are too big to fit in the drain, but you could have issues with smaller fish getting sucked in.
How to Install a Drain
Pond drains are easiest to install before the pond water goes in, so you don’t have to drain the water out. If you decide to install a drain after the fact, it will be a significant headache and probably won’t come out well. If you’ve decided that you want a drain when you’re installing a pond, here are the steps to do it.
- Dig a hole to hold the drain at the lowest part of the hole for the pond. Dig a trench for the plumbing that goes to the filter outside the pond.
- Install the drain and plumbing.
- Place the liner in the pond. Cut out a whole where the drain will sit by putting cutting an “X” in the hole to make sure there is plenty of liner material left to create a watertight seal.
- Put some glue on the top of the drain, then press the liner down.
- Install the flange that came with the drain over the liner material, and screw it to the drain lip.
- Trim the excess liner from inside the drain, and apply another bead of glue to the gasket.
That’s it in a nutshell; the drain you purchase will likely have some additional instructions to get a watertight seal, but it’s not a difficult process if you’re installing your own pond. If you hire it out to a professional, the drain will likely add some expense.
Parts You’ll Need for Your Drain
A pond drain is relatively simple to install, and only requires three basic components; the drain itself, a 3-4” PVC pipe to drain to the outlet, and some sort of outlet component, like a filter. Once your drain is installed, the only piece you should ever have to deal with is the drain’s outlet filter, to clean out on a semi-regular basis.
Types of Ponds
At the end of the day, whether you install a drain depends on the type of pond you have as well as your own preference for whether you want to install one. In the vast majority of cases, a drain isn’t necessary for the pond, but it could help make your life easier or keep fish a little healthier.
The rest of this article will describe in detail several different types of ponds, including koi, swimming, garden, wildlife, and farm ponds, as well as whether each pond could be improved with the addition of a drain.
Koi Ponds
Koi ponds, as the name suggests, are ponds that are intended to house koi fish. Koi fish are different varieties of a species of Asian carp, and are actually related to goldfish. These ponds are carefully designed to help the fish reach their brightest colors and largest size, and larger ponds can house dozens of these fish.
Koi ponds are very popular among fish enthusiasts because of the peaceful and calm environment they can provide. Koi ponds are the types of ponds that can most benefit from a bottom drain, as there is a significant amount of waste generated by the fish. Before drain systems existed, this waste was handled by bottom-feeding bacteria that live in the pond.
Even with that bacteria, however, koi ponds usually needed to be drained at least annually and have the bottom cleaned out. A drain will remove the need for this, however, and will help keep the pond water cleaner and help keep fish healthier. For this reason, it’s recommended to install a drain in your koi pond while you’re installing it.
Swimming Pond
Swimming ponds, also called natural swimming pools, are an alternative to a traditional in-ground pool that uses natural plant life, instead of chemicals, to keep the water clean and clear for swimming. They’re aren’t very popular in the United States but some people have seen the benefits and tried to install their own.
Swimming ponds are on the large side but can also benefit from having a drain installed in the bottom of the pool. Bottom drains can only be effective for areas up to about 16’, but they can help circulate the water at the bottom of the pool better than a filtration system or skimmer, that often only gets the water at the top to circulate.
However, natural swimming pools have the benefit of having a variety of plant life that help keep the water clean and clear. These plants help to filter the water and keep harmful bacteria from setting up shop there.
Garden Pond
Decorative garden ponds are small ponds that are placed in a landscape, and they may not have fish in them. For the purposes of this discussion, a garden pond doesn’t have fish in it. You’ll find that again, a drain may help with keeping your pond clean but it isn’t necessary.
Standing pond water tends to become stagnant if it sits for long periods of time, which will lead to a muck-filled, foul-smelling pit in your backyard. However, this can be mitigated with a small pond pump (link to Amazon) that help circulate the water.
When coupled with weekly or even bi-weekly partial water rotation (where the pond is drained partially and then new water is put in), this will keep most decorative ponds clean and clear. Therefore, having a bottom drain in a small garden pond isn’t necessary but won’t cause much harm, either.
Wildlife Pond
Wildlife ponds are similar to natural swimming pools but they’re usually much larger and are installed for the purpose of giving a natural eco-system to wildlife, as opposed to creating an alternative swimming destination to a traditional pool. Due to its larger size, installing a drain in the bottom of one of these ponds will be very costly and won’t do much to help.
This isn’t to say that a drain won’t help, especially if the pond is on the smaller side. In general, the largest bottom drains with a 4” output can handle a pool up to about 12-16’ in diameter. Anything larger will be too big for the drain to effectively circulate and clean, so it will either take another drain installed or just forego the drains altogether.
Wildlife ponds don’t have to be large, however. Any sort of pond can help provide a welcoming habitat for a variety of wildlife, and the smaller ponds will stay cleaner with a drain. However, another consideration, particularly if the drain uses suction, is whether it will trap smaller creatures. Most people who install a wildlife pond skip the drain for a more natural pond.
Farm Pond
Finally, a farm pond is a very large pond that’s stocked with game fish for fishing purposes, and a drain is not necessary. These ponds can take up several acres, and any drain would have to be an industrial sized drain that would be very costly to install. Larger bodies of water don’t have the same issues with circulation that smaller ponds have either.
Debris and waste in a large pond won’t cause the same issues for the cleanliness of the water either, since the waste is spread out over a larger volume and thus, the water doesn’t have harmful chemicals like ammonia super-concentrated.
Therefore, if you’re installing a farm pond on your property, you can dispense with the bottom drain. It’s definitely over-kill and will probably cause more problems than it solves, as getting to a clog in a drain that has dozens of feet of pipe could be difficult.
Final Thoughts
In the vast majority of cases, a pond doesn’t need a drain in order to function. A small pump and periodic cleaning can solve most of the same issues a drain will solve. There are a couple cases in which a drain might be beneficial though; if you don’t have time for a lot of maintenance and cleaning, or if you have koi fish that require a clean habitat.
A backyard pond can provide a peaceful and serene escape from your daily life, but you want to keep it clean and avoid having it turn into a disgusting pool of standing water. If you’re installing a pond right now, it might be beneficial to just add a drain, since it’s a lot easier to do before there’s water in it. However, whether or not you install a drain is ultimately up to you.