FAQ - Pond - Installing a Liner Pond

1. Calculate the size of the liner needed. To do this, add twice the pond depth to both the length and the width of the pond, then add another 2 feet minimum to make sure you have enough liner around the outside edge. In some conditions, some liners will require underlayment. The liner manufacturer will most often indicate which liners need this protective layer between the liner and certain types of soil. For instance, some liners need underlayement for use with rocky soil.

2. Mark the outline of your pond to be with a rope or garden hose. If you have already ordered your liner, make sure you stick to the size and shape you originally determined.

3. Remove the sod, then dig out the shelves. Most ponds are designed with shelves 9 to 12 inches deep to hold emergent waterplants such as can be found in our Bog Plants section. Make sure to create selves wide enough for an interesting planting. Narrow shelves will limit the number and type of plants that you can add later.

4. Dig the deeper area of the pond.The sides should slope in at an angle of about 20 degrees from verticle. Check to see that the bottom of the pond is level with a board and spirit level. If you are installing a drain in your pond make sure that it is in the deepest spot and that the bottom slopes somewhat in that direction. Next, with a flat spade, cut a ledge 1 to 2 inches deep around the entire edge of the pond for edging material. This will hide the edge of your liner and help hold it in place. Check that edges of the pond are level. If you haven't got a board long enough to reach across your pond you can use a line level instead.

5. Prepare the hole for the liner by removing any stones, roots or sharp objects and by adding 2 to 3 inches of sand to the bottom of the hole. If recomended, add the proper underlayment for your liner at this point.

6. Install the liner. Carefully place the liner in the hole. Wiegh down the edges with a few flat stones or bricks. If a waterfall is part of your design, lay the waterfall liner along the full path of the waterfall, overlapping the pond liner. Start to fill the pond with water. As it fills take time to smooth out as many wrinkles in the liner as possible, some will remain. After the pond has filled somewhat, you can remove the wieghts you used earlier to hold it in place, if they are too close to the edge, they could get pulled into the pond as the liner settles, but make sure that the edge of the liner doesn't fall into the water. After it is full and the liner has fully settled, you can begin to place your edging material. If your edging material extends past the edge of the liner then there is no need to cut it. Anchor the liner with long nails aound the edge of the pond, above the waterline and under the final placement of your edging material. It is best to wait untill the final stages of building your pond to cut off the excess liner in case you need to make some changes to the position or settling of the liner.

7. Add your edging materials. Often coping stones are used for this purpose. One way to prevent the stones from moving and falling into your pond is to mortar them in place. On waterfalls try to place stones to create a natural look. Strategically place stones that create 'jumps' for the water to flow over. This adds to the action and sound of the waterfall.

Mortar is commonly available in sacks at any good hardware store or sand and gravel yard. Dyes, with which you can make the mortar look more like soil and less like cement, are available as well. A cheap, throw-away 4 inch paintbrush is an excellent tool for tamping the mortar into the joints between the stones. When building the waterfall, keep in mind that on a 12 inch wide weir, 1/2 inch of water is equivalent to 10 gallons of water per minute. Bear this in mind when you make the spillways and buy a pump. If your pump won't pump enough water to cover the weir that you build, it will have an entirely different appearance than if the water covers the entire weir. Sheets of water require a good supply of water at the drop off point. Also, if you are planning to put plants into the pools in the stream or waterfall, or onto the weirs, or if you are planning to pinch the flow of the water at a particular point, make sure that the liner goes well above the level of the weir itself and around the entire pool.

8. Trim off any excess liner and finish off with some tastefull landscaping around the edge of your watergarden, making sure that fertilizer run-off from your landscaping or lawn will not be able to flow into the pond and create instant green water. After treating the water to remove chlorine or chloramine you can begin to place your waterplants. Some people prefer to let the water age somewhat before they start planting their pond or adding fish.