Having clean, safe water is an important factor for pond owners, especially those with swimming ponds. Natural swimming ponds are great additions to outdoor areas and provide a space where you can indulge in chemical-free water. But how do you make sure that the swimming pond is as clean and safe as possible? Well, it starts with a sturdy liner that’s properly in place.
In this blog, we’ll take you through how to line a natural swimming pond to make sure it’s up to the standard you need. From how to purchase the right liner for the space to how to actually install it, we’ve got all the tips and tricks. Let’s get into it!
Why Lining Matters in a Natural Swimming Pond
Natural swimming ponds are popular and create a space where people go to be at one with nature. But, when there’s dirt, algae, and all kinds of muck in the water, it’s not as safe as it should be. And it’s not very pleasant!
The lining of the pond matters more than you might think and is a very large aspect as to why some natural ponds are in better condition than others.
Without a proper liner in place:
- Water seeps into the soil, dropping the pond’s water level.
- Soil and debris contaminate the swimming zone.
- Pond walls erode over time.
- Algae and bacteria are harder to manage.
Best Liner Material for Natural Swimming Ponds
Using a liner is so important, and so is the kind of material it’s made from. EPDM rubber liners are considered to be the best, due to their excellent qualities. We stock Rollgum EPDM liners and stand by their strength and durability.
Some of the benefits of using an EPDM liner are:
- Safe for swimmers, fish, and wildlife.
- Flexible enough to fit into curves and plant zones.
- UV and ozone resistant, great for the Australian sun.
- Excellent lifespan (20+ year warranty).
- Ideal for free-form or large ponds.
Step-by-Step Guide: How to Line a Natural Swimming Pond
So, how do you actually line a natural swimming pond?
Here is a step-by-step guide:
Step One: Plan & Excavate
Start with a clear design. Natural swimming ponds typically include:
- Swimming zone: the deeper area for swimming.
- Regeneration zone: a shallower area with plants that naturally filter the water.
- Optional shelves or steps for planting or access.
Excavate the shape with gentle slopes. And, make sure to remove sharp rocks and roots, and any other kind of debris that could puncture the liner.
Step 2: Purchase the Liner
Once you’ve dug the hole where the natural pond will go, you need to work out how much liner you need and purchase it.
To determine the correct liner size, you need to account for:
- The pond’s length.
- The pond’s width.
- The depth (on both sides).
- Any extra overhang (usually around 0.4 m or more on each side).
Use this formula:
- Liner Length = Overhang (one end) + Depth + Pond Length + Depth + Overhang (other end).
- Liner Width = Overhang (one side) + Depth + Pond Width + Depth + Overhang (other side).
Here is an example to help you:
If your pond is:
- 1 m deep
- 4.7 m long
- 3.2 m wide
- And you add a 0.4 m overhang on each side…
Then:
- Liner Length = 0.4 + 1 + 4.7 + 1 + 0.4 = 7.5 m
- Liner Width = 0.4 + 1 + 3.2 + 1 + 0.4 = 6 m
So, you’ll need a liner that is at least 7.5 m x 6 m.
Step 3: Add a Protective Underlay
Before you lay out the EPDM liner, roll out a geotextile underlay first. This works to protect the liner from sharp edges and root regrowth, as these can potentially damage or puncture it. Plus, it keeps the liner safe from ground movement and the problems this can cause.
In some cases, there might be rocks or roots you’d prefer not to remove. Or, you might plan to add rocks or similar features later. If this is the case, it’s best to reinforce those areas with extra layers of EPDM liner and geotextile underlay.
Start with a base layer of geotextile underlay and then lay the main EPDM liner. Then, in the areas where rocks will be placed, add an additional layer of geotextile underlay and top it with a second piece of EPDM liner for added protection.
Step 4: Install the Pond Liner
Once everything’s in place, it’s time to install your pond liner. The best practice is to start with the deepest part and work your way outwards. Make sure to smooth out any creases or wrinkles as you go and allow for the liner to naturally fall into the curves and corners.
As you position the liner, make sure to:
- Leave enough overhang beyond the pond edges to reach into the anchor trench. This ensures a secure and lasting installation.
- Avoid pulling the liner tight. Leaving some slack allows for natural ground movement and settling over time, helping prevent tension and tears.
Your pond might need multiple liners, so you’ll need to seal it together. With Rollgum EPDM liner, this is done using a primer and double-sided seam tape system and no heat or glue is required.
Mark the overlap area with chalk, apply primer, wait until tacky, then apply the seam tape. Then, press the top liner into place and roll over the seam to activate the vulcanising bond.
Step 5: Anchor the Edges
Once the liner is in place, you’ll need to anchor the edges. To do this, tuck the excess liner into the anchor trench around the perimeter to secure it when the liner is properly positioned and conforms to the shape of the pond. Then, backfill the trench with soil to hold the liner firmly in place.
For added stability and a more natural finish, you can:
- Place large rocks or paving stones along the edge.
- Install turf or plants to blend the liner into the surrounding landscape.
While helping to keep the liner secure during changes in water level or weather, these additions also enhance the look of the pond.
Step 6: Fill the Pond and Check for Leaks
The natural swimming pond should look like it’s all coming together now! So, it’s time to fill it with water. Start filling it slowly with clean water and keep an eye on it as it rises. Make sure to check that there are no leaks or problems with the shape of the pond due to the liner.
Closely monitor water levels as it’s filling to catch any sudden drops that could signal a leak. And, check the liner for any shifting, folds, or signs of tension.
Step 7: Add plants and other equipment (if wanted)
Now it’s really time for the fun part. If you want, you can add plants and other equipment to the water now.
You can add aquatic plants such as lilies, reeds, or submerged oxygenators to support water clarity and ecosystem health.
Or, use this opportunity to Install fun equipment like floating lounges, water trampolines, slides, or climbing features to turn your pond into a recreational space.
Tips for Keeping Water Clean and Safe
Lining your natural swimming pond is just the first step. You need to keep it as clean as possible at all times, especially if you want to enjoy swimming there!
Follow these tips to maintain clean, healthy water:
- Install a biofilter or wetland filtration system in the regeneration zone.
- Use aeration systems to oxygenate water and control algae.
- Add native aquatic plants that naturally absorb nutrients.
- Keep debris out with skimmers or pond nets.
- Add probiotics like Biostim each month to keep levels of aerobic “good” bacteria high and competition for nutrients with algae and weed.
- Avoid using any chemical treatments that harm beneficial bacteria.
Final Thoughts
By following this step-by-step guide, you can create a clean and safe natural swimming pond. Choosing the right kind of liner has a lot to do with the health and environment of a pond, so make sure you opt for EPDM. Not only is it extremely durable and long-lasting in all kinds of weather conditions, it’s easy to use and install.
Are you looking for the right pond liner? Take a look at our selection of EPDM pond liners and geotextile underlays for your project. Or, for expert advice on building a natural swimming pond, contact us today.