If you are building a pond, keep in mind design and practical issues.
Locate a pond where it will create a focal point, ideally in a place where it can be viewed and enjoyed from a seating area like a patio or from indoors through a window.
Build a pond that is proportional to the size of your yard.
Make sure your pond will receive at least 6 hours of sun if you want to grow water plants like water lilies.
Factor in ways to facilitate maintenance when pond building. Build in clean-out pipes, bottom drains, skimmers and pump houses that are not difficult to access. Make sure you include adequate filtration, especially if you plant on keeping fish.
Opt for the larger size pond rather than starting small and planning to enlarge your pond. Most people prefer the options you’ll get from a larger sized pond, like more or larger fish, more plants and a larger waterfall. Increasing the size of an already-built pond can be complicated so try to determine the right size from the start.
Avoid steps and ridges in the pond if you have raccoons or other animal pests in your area and plan on having fish. Steps are nice for setting in bog plants, but they also facilitate fishing by predators.
If you don’t plan on having fish, make sure you make provisions to control breeding mosquitoes.
Make sure your pond is at least 1000 gallons and at least 30” deep if you want to keep a few koi. If you want more koi build a larger pond. Koi need large ponds to thrive.
When building your pond plumbing leave plenty of room between pipes and use a larger gauge pipe rather than smaller. Larger pipe will allow for a freer flow of water, and by installing plenty of pipe between events like leaf traps, back flows and the pump itself (if you are using an in-line pump) you will be able to take pipes apart for repairs and have space to add additional mechanical parts. Ideally, stick to 2″ or larger PVC pipe.
Check into your local building codes before building your pond. For example, a pond that is more that 18” deep in California will require a 5’ high fence surrounding it since it will be treated like a swimming pool. A fenced-in pond makes little sense from a decorative point of view in most gardens.
Plan on safety. Pets and children are drawn to ponds and you need to keep in mind protecting them from accidents in or near a pond. Also make sure your pond is not destroyed by your dogs – or from a neighbor dog — since many dogs will find your pond to be an irresistible invitation to go for a swim.
Research, design and plan your pond before you buy materials or dig. Any time you devote to doing your homework is likely to save much more time and expense by avoiding future mistakes and regrets.