Pond liner

Garden fish ponds and water gardens are popular landscape improvements. They attract wildlife such as birds, frogs, and butterflies, and provide a peaceful place to relax. The variety of products on the market today makes installation easy and affordable. There is a type of pond liner for every application so shop around. The biggest error in pond design is making it too small. A good rule of thumb is to make the pond 30% larger than what is envisioned.

pond liner install

Site Location

Selecting the site is extremely important. Is this to be a secluded getaway or a landscape feature to be viewed and enjoyed from inside the house?

If the pond contains plants it needs to receive four to six hours of sunlight a day. Don’t site the pond where rain or sprinkler runoff will flood it or carry debris and other items into it. Keeping it from under trees that shed leaves or needles into the water will keep the pond cleaner. Be certain to locate near a power source if any of the pond components require electricity.

What can I use for a pond liner?

The first requirement for any pond is the ability to hold water. Pond liners with a polyester weave underlay and concrete ponds are good alternatives to natural water features. Pond liner products can be rigid like a preformed pond liner or flexible to conform to custom excavations.

Fiberglass liners now come with a more natural-looking rock finish. The rougher finish also provides a habitat for beneficial bacteria growth. A preformed pond liner is good for a small water garden or backyard pond of 130 gallons or less.

A concrete pond is long-lasting and the most expensive to install. It can also leak toxins into the water for a period of time if not the layers are not properly sealed and requires solid foundations to support the structure.

Ponds should be deep enough not to freeze solid in the winter and can be located in the shade. They require certain types of non-toxic fish pond liners. A Butyl pond liner or a fish grade PVC pond liner is the most commonly used.

Water garden ponds are home to a variety of plants and also need a non-toxic pond liner and one that won’t degrade in sunlight. A water lily pond requires about the same depth and conditions as a fish pond.

Listening to the sound of a waterfall is soothing and relaxing after a hard day’s work. A huge amount of very realistic looking preformed waterfalls is available that are easy to install and give instant gratification. Simple designs are the easiest to work with.

Pond Liner Maintenance

Fighting algae growth is the biggest battle in keeping the pond healthy and attractive. With proper care, the pond will reach a balance where constant vigilance is unnecessary. Algae require sunlight and excessive nutrients to grow.

Broadleaf water plants shade the water and protect it from too much light. They also make use of nutrients and so prevent their buildup.

Plants may need monthly trimming to be kept in check and dying leaves should be removed. Scavengers, such as snails, feed on pond waste thereby performing a necessary service. Pond filters reduce algae but need frequent cleaning to be effective. There are also chemicals that can be used to control algae, but care must be used since they may be toxic to plants and fish.

Butyl Pond Liner Facts

Butyl rubber is the type that many of us think of when we think of rubber. First used to make tire inner tubes in 1931, butyl rubber is now used in a huge variety of applications, including adhesives, sealants, plastic cling film, lubricants, and paper, as well as pond liners. It is airtight and watertight, making it ideal for a pond liner.

Pond liners made of butyl rubber are widely used in the UK. US gardeners tend to favor liners of polyethylene (PVC), which means butyl liners can be hard to find in America.

What thickness pond liner is best?

Butyl rubber pond liners are usually about 45 mm (45/1000th of an inch) thick, heavier than PVC liners, which are usually 20 or 30 mm. Despite this thickness, you will still need to install an underlay to protect and support the liner, and you will need help to get it in. A butyl pond liner will prove more resistant to puncture from rocks or roots than one of PVC would especially if you are going down the road of an aquascape pond.


The biggest advantages butyl liners offer are endurance and flexibility. You can expect a butyl liner to last 15-20 years under normal conditions, and some manufacturers will even offer a lifetime guarantee. It’s worth shopping around to find one who does.

Butyl rubber is resistant to heat and UV radiation from the sun, so it does not dry out and crumble the way some other types of rubber do. It is also proof against burrowing insects and rodents who may damage other types of pond liners in your water garden. Unlike PVC, butyl will not go brittle in cold weather.

Being rubber, butyl pond liners can easily be stretched, cut, and shaped to fit even oddly shaped ponds, which is not easy to do with PVC. The higher thickness does mean they weigh more and can be more difficult to lift and handle, which can be a concern if you’re doing it yourself instead of having it installed professionally.

Another type of liner is EPDM rubber, which uses a synthetic rubber instead of butyl. EPDM (ethylene propylene diene monomer)is slightly cheaper, and is stretchier, and offers even more flexibility. Be aware, though, that a low-quality EPDM pond liner can poison the fish who live in the koi pond. This will not be a concern if you go with butyl.

PVC Pond Liner

Whether building a simple pond for livestock, a landscape water feature, or a full-blown koi pond, a PVC liner is an economical foundation. Offering great flexibility of design, PVC liners with UV stabilizers are the most popular pond lining material for most projects.

In addition to the basic purpose of preventing the pond water from escaping, pond skins pond liners also keep groundwater from seeping into your clean pond through the sides or bottom.

A PVC liner is made from a polyvinyl chloride material that is very similar to swimming pool liners. However, pool liners should not be used because they are embedded with algaecides that can be harmful to plants and fish. Before purchasing any pond liners, be sure that it is labeled safe for aquatic life.

Cheap pond liners will probably not have UV protection and are usually made of a thinner material that is more vulnerable to tears or punctures. A heavier weight material with UV protection will last much longer and many come with a 10-year warranty. Thicker liners are normally embossed to increase the surface area and encourage the growth of beneficial bacteria.

To prevent damage to the liner by roots and stones from below, a durable pond underlay is advisable as a barrier – preferably something strong like a polyester weave underlayment. The underlay provides protection and stability for the pond liner.

For a small decorative pond environment, there are pond kits available that contain everything needed to set up your pond environment for all weather conditions, including step-by-step instructions. With or without a kit, before purchasing pond liners it is necessary to decide on the size and shape of the pond, then calculate the size of liner needed. There are many on-line calculators, but you can also do it yourself with simple math. Once you have determined the dimensions of the pond using a tape measure:

  • Add the longest point of the pond, plus two-times the depth, plus two extra feet.
  • If the pond is five feet at it’s longest part and two feet deep at its deepest point,
  • the length of the liner would need to be 5 + 4 + 2 = 11 feet.
  • Repeat the same process with the widest point of the pond to get the width.
  • For example, if the same pond is three feet wide,
  • the width of the liner is 3 + 4 + 2 = 9 feet.
  • The pond liner then needs to be, at least, 11 x 9 feet to allow for manipulation without the risk of tearing due to over-stretching of the material.
  • Make sure to get a fish safe liner to keep everything healthy and promote bacteria growth.

A one-piece liner will be more leak-proof than one that has seams. Excessive extra material can be folded and tucked under or trimmed. The edges can then be hidden with rocks or potted plants. A carefully constructed pond with a PVC liner can be a beautiful investment that adds value to your property. Just plan ahead and make sure to include locating your pump, skimmer, and other items in the pond if applicable.