How to Build a Backyard Pond: A Step-by-Step Guide

To build a backyard pond you dig the hole in two or three shelves, line it with underlayment and a fish-safe EPDM liner, set a skimmer at one end and a biological filter at the other, run flexible pipe between them, and size the pump so it moves the whole pond volume at least once an hour. A typical first pond is 11 feet by 16 feet and about 2 feet deep, which is roughly 1,500 to 2,000 gallons. Most people finish the build in a weekend with a kit, because a kit means the pump, skimmer, filter, liner and fittings are already matched to each other.

This guide walks the job in order: choosing the type of water feature, sizing the pond, digging it, the liner math, the pump math, filtration and clear water. Earth Stone Rock is an authorized Aquascape dealer, so every sizing rule quoted here is Aquascape's own published guidance rather than a rule of thumb we invented.

Pond, water garden or pondless waterfall: which should you build?

These are three different projects and the decision changes everything downstream, so make it first.

A water garden, also called an ecosystem pond, is the full version: open water, plants, usually fish, a skimmer pulling surface debris and a biological filter feeding a waterfall. It is the one people picture, and the one that needs the most equipment.

A pondless waterfall is a stream and waterfall with no open water at the bottom. The water disappears into a gravel-filled basin and a vault holding the pump, then returns to the top. You get the sound and movement with no standing water, no fish to overwinter and far less maintenance. It is the usual pick for front yards, small spaces and anyone with young children.

A fountain or spitter is the smallest version of all: a self-contained basin, a small pump and a decorative outlet. It fits on a patio and can be running the same afternoon you buy it.

If you are undecided, a pondless waterfall is easier to live with and a pond is more rewarding to look at. Plenty of people build the pondless version first.

How big should a backyard pond be?

Bigger is genuinely easier. A larger volume swings less in temperature, dilutes waste faster and goes green less readily, which is why a 2,000 gallon pond is less work to keep clear than a 300 gallon one. The practical floor for a pond with fish is about 2 feet deep, or 3 feet and more if you intend to keep koi through winter in a cold climate.

Pond size	Depth	Roughly	Suits
6' stream, no pond	basin only	Pondless	Front yards, small spaces, no open water
8' x 11'	2'	~700 gallons	A small backyard pond, plants, a few small fish
11' x 16'	2'	~1,500 gallons	The common first pond. Plants and fish, comfortable margin
21' x 26'	2' to 3'	~4,000 gallons	A feature pond, koi, multiple waterfalls

Pond and waterfall kits

Gallons are approximate, because a real pond has sloped sides and shelves rather than being a box. A kit is the shortcut past the hardest part of this project, which is not the digging but making sure the pump, skimmer, filter and pipe all match. Browse the full range in water feature kits.

How to build a backyard pond, step by step

1. Mark it out and check the site

Lay a rope or garden hose on the ground and live with the shape for a day before you dig. Keep the pond out of the lowest point in the yard so runoff does not drain into it, and away from deciduous trees, because leaves are the biggest source of debris your skimmer will fight. Call your local utility locate service before digging.

2. Dig in shelves, not a bowl

Excavate in two or three levels. A shallow shelf around the rim at roughly 8 to 12 inches holds marginal plants, then step down to the main depth. Slope the walls slightly outward rather than cutting them vertical, which stops them collapsing and makes the rock easier to set.

3. Set the skimmer and the filter

The skimmer goes at the end the prevailing wind blows toward, where floating debris collects. The biological filter goes at the opposite end, at the top of the waterfall. Water leaves through the skimmer, is pushed up to the filter and returns down the falls. That loop is the whole system.

4. Underlayment first, then liner

Remove any sharp stone, then lay geotextile underlayment across the whole hole before the liner goes near it. Underlayment costs a fraction of a liner and is the only thing between a root and a leak. Unfold the liner on a warm day when it is most flexible, working the folds into tidy pleats at the corners rather than stretching it flat.

5. Plumb it

Run flexible pipe from the pump in the skimmer to the inlet on the biological filter, as short and straight as the layout allows. Every elbow and every foot of pipe costs you flow at the waterfall.

6. Rock and gravel

Set the larger stone first, on the shelves and around the rim, then fill between with gravel. Rock is not decoration here. It shields the liner from sunlight, gives beneficial bacteria somewhere to colonize, and hides the liner edge so the pond looks like it belongs in the yard.

7. Fill, start the pump, then wait

Fill the pond, add a dechlorinator and run the pump. Give the biology a few weeks to establish before adding fish. A new pond very often goes green in its first month; that is normal and it passes.

How much pond liner do I need?

Aquascape's published formula is to measure the length and width of the water feature and add the depth twice, because the liner has to go down one side and back up the other. Aquascape's own worked example is that an 11 foot by 16 foot pond takes a 15 foot by 20 foot liner.

• Liner length = pond length + (2 x depth)
• Liner width = pond width + (2 x depth)

So a 10 foot by 15 foot pond at 2 feet deep needs a liner at least 14 by 19 feet. Round up to the next stocked size, and buy the same coverage in underlayment. We stock 45 mil fish-safe EPDM both boxed in pre-cut sizes and by the roll for larger builds and streams.

Liner, underlayment and seam supplies

See everything in liner, pipe and installation.

What size pond pump do I need?

Aquascape's rule is that the pump should circulate the entire pond volume a minimum of once every hour. A 1,500 gallon pond needs a pump moving at least 1,500 gallons per hour. That is the starting number: Aquascape also notes that waterfall height and the length of pipe between pump and falls both reduce delivered flow, so size up rather than down between two models.

To find your volume when you do not have a kit telling you:

length (ft) x width (ft) x average depth (ft) x 7.5 = gallons

A pond 11 by 16 feet averaging 1.5 feet deep works out at about 1,980 gallons, so you want a pump rated at 2,000 gallons per hour or more. Use average depth, not maximum depth, because the shelves take up real volume.

Aquascape sizes the Ultra range from Ultra 400 to Ultra 2000 and the AquaJet range as 600, 1300 and 2000, so matching a model to your number is straightforward. Adjustable-flow pumps are worth the difference if you expect to tune the look of the waterfall, since you can dial flow up or down without changing the pump.

Pond pumps and pump accessories

Compare the full range in pond pumps.

Filtration: what a skimmer and a biological filter each do

These are two different jobs and a pond with fish wants both.

The skimmer is mechanical. It sits at the water line and pulls the surface through a net and a mat, catching leaves before they sink and rot. It also houses the pump, which makes cleaning a two-minute job instead of a wading expedition. Aquascape's Signature Series skimmers come in 200, 400 and 1000 sizes.

The biological filter is where bacteria convert fish waste into something plants can use. It sits at the top of the waterfall, so the filter and the falls are the same piece of the design. On a pondless waterfall the equivalent parts are a vault holding the pump and the modules that create the reservoir under the gravel basin. On a small container water garden or patio feature a single submersible filter is enough on its own; our Submersible Pond Filter product page lists it as sized for ponds up to 800 gallons.

Skimmers, filters and pondless vaults

See the full selection in pond filters and skimmers.

How to keep pond water clear

Clear water is mostly a design outcome rather than a chemical one. Four things do the work: adequate circulation, surface shade from plants and lilies, restraint about how many fish you keep, and keeping leaves out. Get those right and treatments become occasional rather than constant.

Treatments cover the gaps: string algae after a warm spell, a cloudy bloom in a new pond finding its balance, or tap water needing dechlorinating after a top-up. Aquascape's pond range covers clarifying, cleaning, routine maintenance dosing and water conditioning, and the same line includes a separate formulation made for fountains and waterfalls rather than ponds. Dose by pond volume, which is another reason to know your gallons.

Pond water treatments

Browse them all in pond water treatments.

Finishing the pond: light, cover and detail

Lighting doubles the hours you actually use the pond, and a waterfall light set behind the falls does more than the same money spent anywhere else. Low-voltage lighting runs off a transformer and is easy to extend later, so buy a slightly larger transformer than you need today. Cover matters too: fish want somewhere to hide from herons and afternoon sun, which is what a fish cave is for, and netting through fall is the cheapest way to keep a season of leaves off the bottom.

Lighting and finishing touches

See more in pond lighting and power and fountains and mini ponds.

What you need to build a backyard pond

The checklist for a standard ecosystem pond, with where each item lives:

• Pond or waterfall kit, or the parts below bought individually. Water feature kits
• Geotextile underlayment to protect the liner. Liner, pipe and installation
• 45 mil fish-safe EPDM liner, sized by the formula above. Liner, pipe and installation
• Pump rated to turn the pond over at least once an hour. Pond pumps
• Skimmer for mechanical filtration and to house the pump. Filters and skimmers
• Biological filter at the head of the waterfall. Filters and skimmers
• Flexible pipe and fittings between the two. Liner, pipe and installation
• Rock and gravel for the shelves, rim and bottom. Landscape rock and river rock
• Dechlorinator and a starting bacteria dose. Water treatments
• Low-voltage lighting and a transformer. Lighting and power
• Netting, a thermometer and predator deterrents if you are keeping fish. Plant and fish care

The Aquascape range ships direct from the manufacturer, so it arrives separately from any rock or gravel ordered from our California yards.

Frequently asked questions

How deep should a backyard pond be?

About 2 feet for a backyard pond with plants and small fish, which is deep enough for stable water temperature and gives fish somewhere to retreat. Go to 3 feet or more to keep koi through a cold winter. Add a shelf at roughly 8 to 12 inches around part of the rim for marginal plants.

What size pond pump do I need?

Aquascape's guidance is to circulate the entire pond volume at least once every hour, so a 1,500 gallon pond needs a pump rated at 1,500 gallons per hour or more. Waterfall height and pipe length both reduce delivered flow, so choose the larger model when you are between two sizes.

How many gallons is my pond?

Multiply length in feet by width in feet by average depth in feet, then multiply by 7.5. Use average depth rather than maximum depth, because planting shelves take up real volume. An 11 by 16 foot pond averaging 1.5 feet deep holds roughly 1,980 gallons.

How much pond liner do I need?

Take the length and width of the pond and add the depth twice to each, because the liner travels down one side and back up the other. Aquascape's own example is that an 11 foot by 16 foot pond takes a 15 foot by 20 foot liner. Buy the same coverage in underlayment and round up to the next stocked size.

What is a pondless waterfall?

A stream and waterfall with no open pool at the bottom. The water disappears into a gravel-filled basin and a vault housing the pump, then recirculates to the top. You get the sound and movement with no standing water, no fish to overwinter and considerably less maintenance than a full pond.

How do you keep pond water clear?

Circulation, shade, restraint with fish numbers and keeping leaves out do most of the work. A correctly sized pump, plants covering part of the surface, a skimmer catching debris before it sinks and netting through fall will keep most ponds clear. Treatments handle the gaps, such as string algae after warm weather or dechlorinating a top-up.

Can you build a backyard pond yourself?

Yes. A kit-based pond of around 11 by 16 feet is a realistic weekend project for two people with a shovel, and the kit removes the part most people get wrong, which is matching pump, skimmer, filter and pipe to each other. Hire out the excavation if the ground is rocky or the pond is large.

Start your pond

Browse the complete Aquascape pond and water feature range, or go straight to pond and waterfall kits for the matched-components shortcut. For the stone to finish it, our river rock and boulders are what most of these ponds get edged with, and the boulder fountains guide covers the drilled-stone alternative if a full pond is more than you want to take on.