Does A Pond Liner REALLY Need Underlay?

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When installing a pond on your property, there are many steps you can take to ensure that your pond will last well into the next few decades. Some people might be tempted to cut a few corners or skip a few steps, but you should be wise in your decisions when building a pond.

Pond liners should always be accompanied by an underlay. Pond liners are designed to stop the pond water from leaking into the ground. The underlay is also designed to protect that liner from any rips or tears that might occur from sharp rocks underneath the pond.

Should pond liner underlays be attached to the liner? Can you use carpet or newspaper as your underlay? This article will answers all of your underlay questions.

Pond Liner Underlay

Should you really put down an underlay before you install your pond liner? YES! You are about to put GALLONS of water into a pond with a little pond liner on the bottom.

What is going to protect your pond liner from the sharp rocks/sticks/debris underneath it? Nothing! Unless you put down an underlay first, your pond liner is much more susceptible to pokes and tears. Do you want your pond liner to last 25 years or more? Then you really should put down an underlay first.

Underlays are great for numerous reasons. For example, Pond Liners Online states the following about underlays:

-protects the pond liner from being punctured by rocks and rough edged stones buried in the ground

-forms a barrier to the potential risk of damage by rodents

-prevents the liner shifting about due to ground movement

-protective underlay liners are made from synthetic materials so do not rot or deteriorate over time

You might think that you do not need an underlay if you just remove all of the rocks and sharp objects from the ground before you place your pond liner. You would be wrong.

You might be able to get most of the pokey things out of the dirt before you install your liner, but you will never be able to perfectly remove every possible thing that could tear a hole in your liner. And if you were somehow perfect and were indeed able to remove everything from the base of your pond, over time rocks will make their way to the surface and will poke holes in your liner anyways.

In order to put your mind at ease and never have to worry about your pond liner tearing ever again, you should just install an underlay first. It’s safe, it’s easy, and it will be worth it.

Carpet Or Newspaper As Underlay

Another common idea people have is to use old carpet or layers of newspaper under your liner instead of spending the money on synthetic underlay. While this might save you money at first, in the long run, it is a bad idea.

Carpet will begin to rot over time, which will shorten the lifespan of your pond tremendously. It can attract mold and other unwanted bacteria that will cause your pond to smell. If your carpet is made out of synthetic material (such as polypropylene) then you would probably be alright to use it, since that is what most pond underlay is made out of.

However, most carpets are a blend of materials, and even using synthetic carpet you are still taking a risk. Old carpet often has staples or tacks left in it from installation. If you are dead set on using old carpet, make extra sure to remove anything that might tear a hole in your liner (and thus defeating the entire point of using an underlay at all).

Newspaper is another poor idea for an underlay because if your liner tears, your newspaper will get wet, which will increase the rate that it breaks down. Newspaper decomposes after about 6 weeks naturally, so sticking your newspaper down in the dirt to biodegrade will not protect your pond for very long.

Newspaper is also not very strong and will likely be torn by any rocks that could also tear your liner. Overall, newspaper should be avoided.

Installing Underlay

When putting a pond in your garden or backyard, you should always make sure to keep track of the dimensions you are digging. This will make installing an underlay and pond liner much easier.

You will need to measure width and length of your pond, and know how deep it will be. When you measure out the size of your liner, make sure that you purchase underlay that is slightly larger than your liner so that there is some overhang on all sides of the liner.

First, lay down your underlay at the bottom of your pond (make sure to remove large rocks and debris beforehand). If you have more than one section of underlay, you do not need to add seams. You only have to overlap the fabric so that there is not any ground visible.

Next, put down your liner. Make sure to tuck both the underlay and the liner down into any open spaces your pond bottom might have so that you do not create air bubbles when you add your water.

Third, put down any rocks on the boarder of your pond to secure the liner and underlay in place. After your rocks are installed and everything is in its proper place, you are ready to add water to your pond!

Underlay You Might Consider Trying

  1. Geotextile Protective Underlay is an excellent product that is environmentally safe, easy to install, and rot resistant. This product recommends that you install it both below and on top of your pond liner. It is £1.75 per 1 meter.
  2. Pond Underlayment from JustPondLiners is another underlay that you might want to try out. It is mildew and rot resistant, and is also resistant to damage done by insects or rodents. 15 feet is $15.
  3. Pond Underlayment from ThePondGuy comes in many sizes for any pond you might have. Their smallest underlay is 10′ by 10′ and is $24.99, and their largest underlay is 10′ by 80′ and is $159.99.

Thinking of joining 2 pond liners together? Check out our article about joining 2 pond liners to learn how.

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We always wanted a fountain of some kind at our house, but professional installation was just too pricey. So, we decided to make our own little fountain and after learning how, we thought we should share our experiences to help people in our same situation.

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