How to Build a Garden Pond

This guide will help you choose the best way to construct a garden pond which will become a haven for wildlife.

With the advent of modern plastics, liner and pre-formed ponds have overtaken concrete as the preferred method for constructing ponds. Each has particular benefits and disadvantages, and this guide has been designed to help you make up your own mind as to which method you prefer.

Before commencing, bear in mind that, although ponds are straightforward to install, their location should be away from hedges and trees so that leaves do not fall into the water. 

You should also make sure that there is some shade during the day, as too much sunlight will cause problems such as green water, suspended algae and blanket weed. 

Liner

Have a plan in mind of what you want to achieve and outline the desired shape on the ground with rope or sand. Then you can start digging.

Create shelves at different depths to accommodate various types of aquatic plants, perhaps very shallow at 2ins, then 5 ins and wide enough to hold containers, and 18 inches.  Overall depth should be at least 2 ft and 4 ft if you want to keep fish.

It might sound obvious but make sure that the liner you purchase is the correct size for the pond you are building. Measure the length, width and depth of the pond. Then, double the depth and add the length and width. Now add 2 feet for overlapping the pond edge. This will give you the correct size.

The hole must be level so use a spirit level balanced on a block of wood to check all around the sides. Remove any sharp stones or tree roots that may pierce the liner.

Now line the hole with a layer of sand or other material such as old carpet. If possible warm the liner in sunlight to make it more flexible and shape it into the hole, try to keep wrinkles to a minimum and add a little water to help settle it into place.     

Slowly fill with water making sure the liner doesn’t stretch. Trim off any excess liner above the water line and use mortar to fix patio stones or similar around the pond edge to keep the liner in place.

Follow this link to our range of pond liners.

Pre-formed

Place the pond (the correct side up, not upside down) where it is to be positioned and mark out by drawing around the shape in the sand. Next measure the shelves. Then dig out the shape including the shelves but adding about 5cm to the depth to allow for a lining of sand.

Remove any stones or roots as they might pierce the liner. Then place the liner into the hole and adjust the shape if necessary, making sure it is level (use a spirit level balanced on a piece of wood across the width and length of the pond). Once you are satisfied the shape is correct, line the hole with the sand and return the pond and it should fit snugly.

When you are sure the pond is level, use sand to backfill and compact it to prevent the pond from moving as it is filled with water. However carefully installed there’s always a chance of some movement, so once filled, leave the pond for at least one week before adding edging stones, plants or other features.

Follow this link to our pre-formed ponds.

Concrete

First, the hole needs to be dug, about 6 inches below what will be the final depth, making sure that the levels, angles and sides are accurately measured - a formal pond needs to look exactly true.

Then dig a trench, about 4 inches deep by 8 inches across, around the sides at the base of the hole and fill this trench with concrete to provide foundations for the walls.   

With the bottom of the hole level, add a layer of sand, compact it firmly adjacent to the wall foundations, and lay 3 inches of concrete. Allow to dry, then add some galvanised mesh and pour another 3 inches of concrete on top. Once the cement has dried use breeze blocks to form the walls, filling in any gaps and hollows with concrete.

After 48 hours, dampen the walls and skim the entire hole with a ½ inch layer of fibre reinforced cement. Next, use mortar to fix an edging of bricks and slabs, allowing for a 2 or 3-inch overhang. Paint the inside with a good quality waterproof sealant, when that is dry you can introduce water.  

Finally, bear in mind that for all types of pond, filters, lights and other features will need electrical and hose connections, so remember to allow space for these while adding any edging materials.

 


Pond header pool in a beautiful garden.Header Pools

A header pool will sit above the level of your pond and is fed by a pond pump. A watercourse or waterfall is then created which returns the water back to the pond. This movement of water not only looks impressive, it also has added benefits for your pond and fish through oxygenation.

When oxygen levels increase, so do beneficial bacteria levels in the pond. This bacteria helps to break down sludge and silt which cause water quality problems. Increasing this bacteria also means that your filter is going to be much more efficient and effective.

So just by adding a header pool you will improve your pond's quality for plant and live stock, the size of your pond will increase, giving you more to enjoy, and you will create an attractive water feature.

What Equipment Will I Need?

Here are some items you're going to need before you're able to begin building your header pool. 

  • Rockery stone
  • Pond liner (0.75mm thick EPDM)
  • Underlay
  • Spade

Preparing Your Header Pool

The header pool in the photographs is located on ground which was already slightly higher than the pond level. Dig down slightly and then build up the sides with rocks. Place the underlay over the potential header pool area and over the rocks at the sides.

The mouth of the header pool should be lower than the rest of the sides of the pool, this allows the water to run out of the pool at the correct place when the water gets to a certain height. You can either build the mouth up slightly lower than the sides with the liner or have it flat level with the height of the bottom of the header pool and block it up with rocks so the water runs between them.

After laying the underlay make any adjustments to the sides by moving the rocks underneath until you're happy with the shape of the pool and the height of the edges. Depending on how deep you want the header pool you would have two options in this scenario, either dig deeper or build up the walls higher. 

Lay Your Pond Liner

The next step is to lay the pond liner on top of the underlay which is there to protect it from any sharp stones.

Make sure to run my liner down the stepped area and into the pond, this prevents any water loss which could be caused if the liner wasn't running all the way down. This is because water can run back under the rocks and, if there wasn't a liner underneath, the water would then potentially drain the pond.

Begin Testing the Pool

Before you start to lay your decorative elements such as heavy rockery stones or anything else, begin testing to see whether there are any leaks or if there are any adjustments to be made.

Start Decorating Your Header Pool

If the testing all went well and you're happy with the layout then you can now begin the decorate the pool. Place rocks at the mouth of the header pool. These rocks allow the water to build up in the pool rather than gushing straight out so that a regulated flow into the pond is crated.

Water flowing through and over the rocks creates the best sound, so be prepared to stand back to have a look and listen, and then maybe change the arrangement until you find what works best.

How is the Header Pool Filled Up?

Your header pool should be fed with your pond pump, you can either do this by placing a filter box behind the header pool or running a pipe from your pump directly into the pool.

Can I Put Fish in the Header Pool?

You can keep fish in the header pool if it's big and deep enough, if not then I'd say this could be cruel as they wouldn't have space to move around freely and could get stuck in the waterfall. The best advice is to keep them in the main pond.

Where Should I Locate My Header Pool?

Remember that if it's in full sunlight then you're likely to have blanket weed problems. This is exacerbated in a header pool as they're normally not as deep, and shallow water is easier for blanket weed to thrive in.