Using pond liner in a concrete pond

by Rita
(Portland, OR)

Hi, Doug- Avid reader of and love your newsletter and articles. I have a concrete pond, 5'x12'x 3' deep. It has developed a significant leak - 6"-8" water loss in a day. The water has stopped leaking, so I suspect we're below the level of the leak. no obvious cracks, but places where what appears to be a skim coat of cement (or something liek it) has fallen off the wall. There are a number of areas that, when tapped, sound hollow as though the skimcoat is pulling away from the wall. I'm pretty sure my best route (cheapest, most effective) is to line the pond with pond liner. How do I adhere it to the walls? Work it around the base of the waterfall platform? Where do I start? HELP!

Doug says that the good news is that you won't have to glue the liner to the walls. Water pressure will hold it in place. You do have to protect the liner with underlay between the liner and the concrete so there is no rub between them and sharper projections from the concrete don't work on the liner.

Working around the base of the waterfall is more problematic. I'm assuming the waterfall is unlined and concreted as well. At this point, you can remove the rocks or concrete as far back as you can, insert the liner "under" the concrete or into a small trench you've made in it. Get some pond foam and foam the heck out of it to make a watertight seal. Then lay rocks back in and over the liner to give you a landscaped look. You'll lay rocks on the waterfall liner as well as the pond liner to hide it.

Do see the construction areas for how to lay in rocks etc.

Hope that helps a bit