From formal ponds to rocky pools water is the one element that can really bring it to life. And in a small London garden it can really make all the difference especially on one of those long hot days we've been having this summer.

At a very basic level you need to choose between formal and informal. In small, angular London gardens a well executed formal pond, either above or below ground level can look brilliant. Edged in brick or stone and reflecting the lines of the house, a deep formal pond can really set off a house and provide year round interest. A large reflecting pond brings the sky into the garden and lighting can extend its use into the evening.

There's a lot of work involved in building and maintaining a pond. Formal shapes are often constructed with concrete blocks and rendered to allow you to paint the pond whatever colour you want - but be careful that paint and sealants are not going to harm fish and wildlife. Pets will also drink from a pond so bear this in mind especially allowing for animals to climb out if they fall in. Provide an easy exit via a shelf or shallow end.

There are also some great contemporary water sculptures available which are often suited to small gardens. I've always been an advocate of you get what you pay for and work with some great people to install real works of water art. Art in the Landscape (artinthelandscape.com) have some brilliant wall mounted pieces. But that's not for everyone and you can pick up some pretty good 'takeaway' pieces at garden centres and DIY stores. These can be easy to install but often give little scope for planting.

I'm going through a bit of a wild water phase at the moment and have been commissioned to design a number of informal ponds that I feel are often better for encouraging wildlife into the garden. They are also better for animal safety as a slowly sloping shelf for escape can be incorporated easily. This sort of pond can be a lot more relaxed and easier to construct although you still need to check levels are right and allow for shelves and plenty of room for fish. On balance you need a larger garden for an informal pond.

Remember that maintenance of ponds is quite high. Keeping the water clean is important for animals that use it and the look of the pond. Use simple pumps with filters on smaller features and consider external filter systems and ultra violet lamps for stopping algae growth. You can look after small ponds very simply and garden centres sell complete kits to get you started quickly, but for larger ponds and more complicated features you will need to call in expert advice.

Once your pond is built start to add plantlife, consider lighting and of course fish, they are high maintenance but well worth the effort. Provide hiding places for them to protect from passing herons is important and remember they need looking after year round. Local aquatic centres can give you good advice on care.

Whichever direction you take remember that water can bring a whole new dimension into your garden and transform it into something magical.

Water can be dangerous if not treated with respect and forethought. We do not recommend ponds for gardens where there are young children but there are plenty of safe features available to get the sound of water without the danger. And don't forget to get a qualified electrician to install and power, pumps and lighting.