There are a number of options on how to line the pond, nowadays there are many rigid liners that you can just drop in the ground. You can also line it with concrete, flexible butile liners and even clay. I always find the liner the most effective because you can make the pond any shape you want. You will need to excavate the pond and then remove any stones and roots from the bottom because they may puncture the liner. Then line the bottom and sides with an inch or so of sand, I find builder's float really handy for this.

Carefully position the liner stretched over the pond and anchored at each corner and along the edges with a heavy weight (paving slabs are perfect). Put the hose in and turn it on. The weight of the water, as it builds up, will pull the liner into the pond forming a nice fit. You will then need to cut the excess liner and cover the edges. There are many ways of doing this - you could use turf, paving, or simply tuck it into the soil and plant around it. It is also a great idea to pinch a bucket of water from a local pond to add to your new pond. This will introduce lots the little creatures and micro-organisms that will benefit your pond.

Water lilies (Nymphaea) are by far the most popular aquatic plant and everybody wants them in their ponds. They come in a massive range of flower size, flower colour, leaf size, and spread - so careful selection is needed.

Some will only spread a few feet where others will take over a 15sq metre pond in a matter of a few years. The golden rule for selecting water lilies is to choose one that will not cover more than half the ponds surface. They come in four main groups dwarf, small, medium and vigorous.

I would suggest you get a good book on water gardening which lists the varieties and what pond they would suit. When you plant them you will need to pop them in so that the young leaves float on top and as they grow lower the pot until it reaches the bottom of the pond. If the leaves then go on to grow above the water level either you have chosen the wrong plant for the depth of your pond, or if this only happens after a few years then it is time to lift and divide the rhizomes, repot and throw them back in!

Good luck!

Sven