How to Make a Pond Safe for Swimming (12 Steps)

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Ponds are usually made for fish and plants, so there are many things to consider when creating a “swimming pond”. Jam Smooth / CC BY-SA 2.0

Not all bodies of water are safe for entering and wading across, let alone swimming! Even shallow ponds can spell disaster for curious swimmers, especially if the pond bottom is wholly natural or if the water is murky. It’s always much safer to swim in designated, fully-fenced areas, such as a properly-managed pool facility.

Nonetheless, it may be compelling to create a large, garden pond that is relatively safe for the avid swimmer. This way, you’ll never have to leave your home for a relaxing dip in nature.

A pond will always be different from a pool in the sense that it is made to support its own ecosystem. Though its water can be circulated and cleansed by top-quality pumps and filters, garden ponds are normally constructed for ornamental plants and fish, and not exclusively for human use. In contrast, swimming pools are considered fully artificial water systems. To make these safe for human use, they are pumped with high concentrations of chlorinated water.

To create a “swimming pond”, you’ll have to forego some natural pond features and be ready to make serious considerations on health and safety. To fully grasp what needs to be done to make a pond safe for swimming, it is necessary to go over certain dangers and conditions.

Minimum Requirements for a “Safe” Pond

Ponds should be wide enough and deep enough to support full body movements while swimming. Michael Coghlan / CC BY-SA 2.0

For a pond to safely accommodate swimmers, it must be large and deep enough to allow for full-body movements. You definitely wouldn’t want to get trapped in a flurry of edge plants or be restricted to just a few feet of free space. Depth is also quite important for remaining afloat. In shallow ponds, swimmers may simply sink to the bottom or be in more danger of slipping and injuring themselves.

Shallow koi pond
A pond for “safe” swimming should not be too shallow, as injuries are more likely to occur. brewbooks from near Seattle, USA, CC BY-SA 2.0, via Wikimedia Commons

Ideally, “swimming ponds” should have a depth of at least 5.5 feet and a length of about 25 – 30 feet. This should be enough space to create a distinct swim zone and plant zone. Anything smaller may simply be regarded as a natural “plunge pool”. Larger-sized ponds are, of course, more ideal as they would provide a bounty of space for free movement and reduce chances of collisions and entanglements.

Apart from large dimensions, you would also have to consider the safety of the pond floor, margins, edges, points of entry and exit, and ease of maintenance. The quality of water is also extremely important, as illustrated by some of the dangers discussed below. Dirty pond water is often the harbinger of many water-borne diseases and potential accidents.  

Dangers of Swimming in Ponds

E. coli bacteria
To be considered safe for swimming, a pond must have less than 150 E. coli colonies per mL of water. NIAID, CC BY 2.0, via Wikimedia Commons

As a freshwater ecosystem, the outdoor pond is rife with life and the abiotic components that they need to sustain them. Every droplet of water contains microscopic particles and microbes, such as bacteria, algae, zooplankton, fungi, and protists. While many of these are harmless, especially when present in controlled numbers, some of these are pathogens that pose serious dangers.

Water-borne diseases are often transmitted through contaminated freshwater systems. They may be carried from place to place by wild animals or be introduced into a system via a polluted water source. Coliform bacteria are some of the most common pathogens that are present wherever warm-bodied animals excrete their waste. This means that if wild animals or domesticated pets have access to your pond, there’s a high likelihood that these bacteria are present there. To be safe for swimming, ponds must have less than 150 colonies of E. coli bacteria per mL of water.

Other pathogens include protozoans that are present on natural sediments and in the water column. Some of these, such as Cryptosporidium and Giardia, occur in virtually all types of freshwater systems. If contaminated water is swallowed by accident, these can wreak havoc on the digestive system and cause a variety of gut problems that may require professional treatment. Some water-borne parasites may also enter the body by burrowing through the skin. They can cause long-lasting rashes (e.g. “swimmer’s itch”).

Dangerous animals, such as snakes, snapping turtles, leeches, alligators, and other opportunistic carnivores, may lurk in pond water or along the pond’s edge. Their bites can cause serious and traumatizing injuries. Some of them may be poisonous and may potentially infect the bloodstream. Harmful algal species, along with those that may occur in blooms, can produce toxic compounds. When ingested, these may result in troublesome gastrointestinal disorders. 

Lastly, physical components can also ruin a morning dip at the pond. Slimy and slippery edges often cause accidents upon entry or exit into the pond. Hidden shards of sharp rocks, metal waste, sunken twigs and logs, and densely occurring submerged plants can cause injuries or be extremely bothersome. The list of potential dangers is rather intimidating, but it takes just a few steps and a good measure of resolve to keep a swimmer-friendly pond!

Steps to Increase Pond Safety for Swimming

1) Run a fully functional filter

Clear pond
A good pond filter helps to maintain water clarity, which is an important part of any healthy pond ecosystem. Michael Coghlan / CC BY-SA 2.0

Pathogens are less likely to accumulate in ponds with consistently desirable water parameters. A fully-functional filter that is adequately sized for your pond would significantly reduce waste build-up. This would help maintain water clarity, which is extremely important for a healthy pond ecosystem. Without a filter, most pond debris and suspended sediments may remain in the water column or sink to the bottom, causing anoxic conditions.

2) Maintain water flow

Water fountain in pond
Adding a water feature to a pond helps to prevent water from stagnating, which stops pathogen buildup. David J / CC BY 2.0

Add a water feature, such as a waterfall or a fountain, to simulate a current in the pond. Moving water is just as important for the prevention of pathogen buildup as pond filtration. You can also place pond pumps in key areas to get the water moving and increase dissolved oxygen levels. Stagnant water serves as a breeding ground for unwanted bacteria and many undesirable aquatic insects.

3) Check the water source

Pond pipe
A polluted water source may be the cause of pathogens and contaminants in your pond. Photo from pxhere

Oftentimes, contaminants and pathogens may be present in your pond as soon as it is filled. If the water source is polluted, damaged, compromised, or ill-maintained, it would likely carry dangerous levels of bacteria and potentially harmful effluents. Pipes that are located close to farms, feedlots, polluted water bodies, and processing plants that produce hazardous waste are subject to exposure. If you suspect that your water source is contaminated, make sure to have an accredited laboratory check for abnormalities.

4) Remove floating debris and insects

Leaves in pond
It’s important to regularly remove floating pond debris as they can quickly become sites of bacterial growth. Lera Shvets / CC BY 2.0

Use a net to regularly remove floating debris before it can sink onto the pond bottom. Detritus often enter the pond through the surface, particularly if they have fallen from overhanging or edge trees. Make sure to remove these, along with any decaying plants and organic materials (such as dead insects), as they become sites of bacterial growth. If a high concentration of debris settles onto the pond bottom, their decomposition can strip the pond of oxygen. These may also clog up the pond filter.

5) Test the water quality often

Water testing kit
You should test your pond’s water quality at least once a week. Glen Bledsoe / CC BY 2.0

Visually inspecting the water isn’t enough to detect whether there are nutrient imbalances that may eventually cause ecological shifts. Unhealthy levels of ammonia and nitrite and low levels of oxygen are seldom evident within the first few hours to days. It takes time for these imbalances to damage a formerly stable pond system. When there are already visible signs of their occurrence, the resulting conditions may be irreversible without a massive water change. Aim to test your pond’s parameters at least once a week for good measure.

6) Build stairs or a dock for entry

Pond dock
Having a pond dock is a great way to provide easy entry into the pond and prevent injuries. Danielle Scott / CC BY-SA 2.0

Ponds are sites of algal growth, and filamentous algae can often be extremely slippery. Mosses, oftentimes just as slippery, also tend to settle on marginal stones. Entry and exit points should be fashioned to prevent injury.

A firm, railed staircase that leads into the pond water should help prevent accidents, but a slightly elevated dock could be even better. The platform should be high enough to keep clear of the water’s surface, yet low enough for persons to enter the pond without making a big splash. The dock should be equipped with a ladder to facilitate an easy exit.

7) Remove sharp objects

Pond with waterfall
Pond plants with spikes or thorns & sharp objects such as rocks should be removed to avoid injuries while swimming. Photo from Max Pixel

Prior to filling in the pond with water, or whenever you conduct a water change, make sure to remove any sharp objects that may have settled into the pond. Remove any naturally occurring rocks with sharp edges and any wooden materials with splinters that may injure unwary swimmers. Submerged and marginal plants with spines or thorns should also be removed from the pond.

8) Line the pond bottom

Pond liner
Lining your pond bottom can prevent injuries and high turbidity levels. A.Fiebig, Public domain, via Wikimedia Commons

Natural pond bottoms are a recipe for feet rashes, nips and stings from curious worms and hungry insect larvae, and wounds from sharp components of the substrate or any rooted plants. Apart from being gentler and safer to stand on with bare feet, pond liners help prevent turbidity levels from becoming too unmanageable. They trap underlying and lateral substrates so that they don’t become eroded or suspended. They also prevent the pond water from seeping into the underlying substrates.

9) Fence your garden or pond

Garden fence
Having a fence around your garden or pond is a good way to stop wild animals from visiting and bringing bacteria into the water. R. Miller / CC BY 2.0

Wild animals are vectors of diseases and parasites. They may often visit garden ponds to feed or quench their thirst. Some large reptiles and amphibians are known for making their way into private ponds. They may become semi-permanent residents of the pond system, creating subsequent generations that will eventually dominate the pond. While most species may not be dangerous, their waste production may place unnecessary pressure on the pond’s filtration system. Moreover, their waste may house the cysts of many parasites

Household pets should also be kept away from the pond as their waste can enter the pond. The presence of dog urine in a pond can cause leptospirosis. This bacterial disease is the result of pathogens that are often present in animal urine. Once the bacteria enter the human bloodstream (such as through a scratch or wound), they can cause fever-like symptoms.

10) Avoid using pesticides close to the pond

Garden pond with plants
Try to avoid using pesticides near the pond, as they can enter the water via water runoff. Michael Garlick / CC BY-SA 2.0

Pesticides can enter the pond via water runoff. If your pond has naturalized edging, chances are that a fair amount of rainfall or garden flooding can cause external materials to enter the pond. Runoff tends to carry many inorganic particles that can alter the pond’s chemistry.

11) Use electrical equipment that has been approved for actual swimming pools

Pool lights
If you wish to use electrical equipment in a swimming pond, it may be safer to use equipment designed for pools. Photo from PublicDomainPictures

Many types of pond industry equipment are not specifically made for use in “swimming ponds”. They may lack the necessary ratings or official approvals for equipment that can safely be used in actual swimming pools. Some pond lights, submersible pumps, and filters are simply not made to be 100% safe in the event of electrical issues. This means electric shock is always a possibility, especially with equipment that is not grounded.

12) Pondside supervision

Large pond
Adult supervision is definitely advised if children or teenagers are swimming in a pond. Amy Aletheia Cahill / CC BY-SA 2.0

If the “swimmers” in question are children or adolescents, then pondside supervision is definitely advised. It’s simply impossible to ensure total safety in an outdoor body of freshwater, as accidents can always happen. It helps to have a responsible and sober adult be present whenever someone is in the water so that a thoughtful response to accidents can take place in a timely manner. A first aid kit for outdoor use should be accessible at all times.

Can You Swim With Ornamental Fish?

Koi pond
Swimming in a pond with fish such as koi & goldfish is generally safe, but may cause them stress. Valerie Everett / CC BY-SA 2.0

It is generally safe to be in the water with popular pond species, such as koi and goldfish. Some recreational ponds, which are made precisely for the experience of swimming and relaxing “in nature”, are stocked with a few of these fish. In establishments that are known for their recreational fish ponds, the koi are likely well-adjusted to being surrounded by humans. Their ponds are also very large and are usually maintained by a dedicated team of experts.

Regardless, while swimming with beautiful fish can be an invigorating experience for us, our presence may be quite stressful for them. If you intend for your pond to be both a swimming area and an ecosystem for fish, you may have to reconsider your priorities or be extremely diligent when it comes to keeping your fish comfortable.

Sudden movements and splashes can disorient fish and scare them into hiding. The stress can affect their appetites and increase their susceptibility to diseases. The pond must be large enough to dissipate swimming-related vibrations. Additionally, visiting swimmers must agree to respect the resident fish!

Chris G
About the author

Chris G

Pond consultant and long-time hobbyist who enjoys writing in his spare time and sharing knowledge with other passionate pond owners. Experienced with pond installation, fish stocking, water quality testing, algae control and the troubleshooting of day-to-day pond related problems.

Read more about Pond Informer.

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