Basic Liner Info and Installation for Dummies

Our Team of Experts

Basic Liner info for dummies...and useful hints for the rest of us.

Lets talk about flexible liners...

We are not here to get into all the controversy surrounding flexible liners. WARNING: if you have not heard about all the pros and cons of using pool liners, roofing liners, EPDM, etc. then never mind and skip the following paragraph and save yourself some time.

First of all this is our opinion, what we have tried, used, failed at, had success with and so forth. You can do as you please, your pond, your rules, remember? As far as pool liners are concerned... we do not like them because of the color, normally blue, and their thickness, 20 to 30 mil seems to be to thin to withstand the punishment of someone stepping on a stone while wading in the pond. We are not even going to discuss the 4 or 8 mil plastic junk here, except to say that our first pond was made out of some of this stuff and lasted about three months. Now the biggie... EPDM 45mil rubber. Pond safe or roofing liner?
NO, NO, NO, we are not going to get in to it... Click here to E-Mail us and we will give you our opinion. For this text we will just say that EPDM 45mil liner is what we recommend.

Okay, for all of you who skipped the above paragraph and saved yourself some time and those of you who had to read it anyway, we are now going to discuss the use of flexible 45mil EPDM rubber liner... in our opinion the only stuff to use.

To help put all this together, lets build an inground pond that should sustain life, which is what most of us want. Dig a hole, go out and buy the right size liner and put it in the hole. For the first time in this text that is not that far off base. You see, that is the nice thing about flexible liners...hey, they are flexible. They conform to the hole that you dig for the most part. NOTE: You noticed that we underlined and highlighted the right size liner above, well that is important and here is why...

You could dig a hole that is to big for your liner, which is a waste of hole digging energy, so do not buy the liner until you are sure of the right size to get. Which brings us back to planning. Keep in mind in the planning stage to account for any underwater features you want in your pond. Shelves for plants, deep holes for wintering, slopes, etc. We are about to talk about liner size vs. hole size, but we also do not want to get real complicated here, so we are going to try and make this as simple as possible. Keep in mind a couple of things we have learned from experience:

The best time to plan for underwater features, ledges, coves, etc. is before you take that first shovel full of dirt.

The best time to plan for a stream or waterfall is before you buy the liner.

The easiest sizes of liners to obtain are the 10 and 20 foot wide stuff.

Liners are a pain in the to patch together.

In order for a liner to fit properly in the hole: The liner must run from past the outside lip of the hole, down the side wall of the hole, across the bottom of the hole laying flat to the deepest part of the hole, up the other side wall of the hole, and over the lip of the other side of the hole. Oh yes, in both directions... length and width. That should be common sense, but sadly some of us did not understand that. Not to mention names, but it was us. (Another dumb mistake, one that now you do not have to make, no need to thank us it is our job.) The formula for all this is: Length + twice the depth for one side of the liner and width + twice the depth for the other side of the liner. Example if your pond (the hole) is 6 feet long and 6 feet wide and 2 feet deep you will need a liner that is 10 X 10. 6 feet to run across the bottom, plus 2 feet to come up one side, plus two feet to come up the other side...6 + 2 +2 = 10.

That being said let us now get into the variables.
Most that has been written about pond construction tells us to make the pond sides level with each other. This is good in the respect that when the pond is full, the water level is equal all the way around the edges. We also recommend that in actual construction you want your pond lip to be level all the way around, but somewhat higher than the surrounding ground level. Remember your pond in most cases, since it is in-ground, is going to be the lowest point in the area where you install it. Water seeks the lowest level. If the lip of your pond is lower than your lawn, then anything you pour on your lawn, like chemicals, weed killers, fertilizers etc., will sooner or later flow into your pond.

SKIPPY SEZ: If you frame in your pond with 2"x6" boards stood on end about 12 inches back from the lip and secured into the ground with 1/2 inch conduit pipes driven into the ground behind the boards, this makes a nice barrier where you can bring the liner up and over the boards where it can be secured by screwing a few slats of wood to the outside of the boards wedging the liner in-between. Also, a couple of other benefits of this design is that you create a under water shelf where you can put bog plants etc. and since the water when full, is actually higher than the surrounding ground by 4 to 6 inches it softens the sides of your pond and looks more natural. Click on these pictures to see the procedure: Picture 1, Picture 2, Picture 3, and Picture 4.

If Mom had put a liner under the Colorado river a few million years ago we would not now have the Grand Canyon, which in turn means we would not need National Park service employees, which in turn means there would not be so much of a budget crunch, which means we would not need a congressional committee to over see the budget, which means we would not need as many congressmen, which in our opinion would be a good thing. Not having congressmen we mean, the Grand Canyon is okay. But do you want the start of a canyon in your back yard? Water is the most powerful force on earth. The absolute best time to plan for a waterfall and/or stream leading into the pond is before you buy the liner. Patching together a couple of pieces of liner is a pain, take our word for it. If you can plan ahead and get a liner that is long enough that your entire system, from pond, through a stream, and up to the top of the waterfall in contained in one continuous piece of liner, that is good, real good. As we stated earlier the easiest sizes of liners to obtain are either 10ft or 20ft wide. As far as length is concerned, they can come prepackaged up to 30 or more feet long and if you get a roll of the stuff they can be even 100ft long. So if you are planning for example to put in a pond that is 6ft wide, 2ft deep, 10ft long, with a 3ft stream leading to a 2ft high waterfall, the math for the liner works out this way. 6ft (width of pond) + 2ft (depth of pond) + 2ft (depth of pond again) = 10ft This is the minimum width liner you can use.

SKIPPY SEZ: If you are going to also use our recommended construction process utilizing the 2"x6" boards stood on end as explained above, you will have to add another 4ft to the width of the liner to compensate for the extra area. 1ft + 1ft = 2ft to cover the set back from the lip...Plus an additional 1ft to 18" to run up the boards and over them.

That covers the width part of your pond. Now the length...
10ft (length of the pond) + 2ft (depth of pond) + 2ft (depth of pond again) PLUS 3ft (length of stream, Note: we are assuming that your stream is smaller in width and depth than your pond so the above width size will be ample, mini tip... during planning you should have some type of lip running down both sides of your stream to contain the water in the direction you want it to flow, remember the Grand Canyon?
Where are we at? Oh ya, we have 10ft + 2ft + 2ft + 3ft which equals the length of the pond and the stream or 17feet to this point. Now add 2ft (to run up the waterfall face) = 19ft.
Recap: To build a pond that is 6ft wide, 2ft deep, 10 ft long, with a 3ft stream and 2ft high water fall you need a liner that is at least 10ft x 19ft. If you incorporate the set back 2"x6" boards as in our recommended method then that liner needs to be at least 14ft wide X 22ft long.

SKIPPY SEZ: More liner is better than less liner. In the above illustration we would buy a liner that is 15ft x 25ft. ....If you can find it; most likely you will be looking at a 20ft x 25ft piece.
Confused yet, well we will try harder. Do this...Dig a hole. There is nothing that says that you can not dig the hole first then take a flexible tape measure and run it from the lip of one side of your pond, down the side, across the bottom, up the other side and over the lip to the other side of your pond and get the exact measurement of the width of the liner you need. Do the same for the length and you got the right measurements for the size liner that will work. Why did we not say that right up front? Because we wanted to give you some basic information to use when you are just in the planning stage of your project. Some people like to cost out every thing before they actually do it. A word about costs... the most important part of your pond besides the water is the way that water is contained... the liner. Do yourself a favor and do not skimp on this aspect of construction. Get a full 45mil thick EPDM rubber liner. For some reason people seem to want to try every thing from pool liners to plastic drop cloths, but we have not found anything that works better and longer than EPDM. However, like we just said, before you actually purchase that liner and start to lay it in your pond it is a good idea to take that final measurement as stated above. Also during planning, consider that 10ft and 20ft wide liners are easy to find.

Okay, let us say that you are smarter than we were, (which is not to hard) and you have gotten the right size liner to fit your pond. The next step is to put something between the ground and the liner. Something that protects your liner from punctures by roots, small rocks, etc. This happens when you get into your pond when it is full of water and walk around... yes, you will get into your pond and walk around, take our word for it. You can go out and buy a under liner-liner, but we think that is a waste of money. If you just put a 1/4" layer of wet newspapers down and line the hole with them it works just fine as a cushion to protect the liner from the ground. Why wet? This is a mini tip... when the newspaper is wet, it will stick to the side walls and will not blow around while you put in the liner. Also do not get into your pond with 3" spiked high heels on. Get the point? What you want to do after you have lined the hole with newspaper or other type of protection is to lay the liner in the hole and fit it to the bottom and sides as best as possible.
DO NOT worry that there are going to be wrinkles, just fold and smooth out the liner as best you can. (The pressure of the water does great things to wrinkles.) When done you will quickly see if you bought the right size liner. It either fits or you are on your way back to try and get an exchange. OR you will have to fill in some of the hole. Your choice. HOWEVER, BEFORE you secure the ends of the liner, by either screwing it to the boards by using our recommended method or other means, you will want to fill the pond. As the water fills the pond you can get in and straighten out the wrinkles, a pull here, a tuck here, and soon the liner fits! When you are absolutely sure it fits, then secure it.

Do you want to know how many gallon your pond holds? Yes you do, we all do and for several reasons which are discussed under the headings of Pumps etc. and also under Additives. Well, there are a couple of ways. When the pond is completely full, get a one gallon milk jug and scoop out all the water while counting. (We hope you understand that was a joke) You can get an estimate of the gallons by taking the length X width X average depth X 7.5. You noticed we said estimate and the reason is the average depth measurement. Most ponds do not have straight sides going down to a flat bottom. Another way is that some hardware stores sell a devise that you can attach to your garden hose that will measure the flow through the hose, but common sense tells us we need to attach this devise before we start filling the pond.

You got a pond. A still, fresh, uninhabited pond. Life begins. Right from the start Mom starts her work and begins to prepare that water you just put in the pond so things can breed, live and die. Just take our word for it...all right? More on this later.

SKIPPY SEZ: Do Not Get Nuts! Water gardening is a fun and relaxing hobby. You can build a pond and enjoy it. Take your time and gather as much information as you can. Ask for advice.
Learn from other's mistakes and do not beat yourself up over your own mistakes.

Whether you have an established pond or are just thinking about putting your first one in, check out our FREE ADVICE PAGE and then we invite you to call our Help Line:

(313) 382-POND or
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Last updated November 21, 1999
Page Creation by Carl W. Richardson (