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natural swimming pool training
We offer training for both individuals and groups.

natural swimming pool training
Join our discussion covering all aspects of pool building and maintenance.

natural swimming pond algae
Natural ponds can suffer from algae. We have found this product that helps.

natural swimming pool liners
If you are after liners
or underlay we recommend Flexible Lining Products.
natural swimming pond construction

What's Involved in creating your Natural Swimming Pond

Surveying the site

Understanding your site is essential. You need to know if any services are in the vicinity and whether any large trees could cause a problem with roots within the natural pool area. Cutting through large roots could destabilise a tree. Also, the natural eco system requires sunlight so you don’t want too much shade.

You need to find out about the height of the water table. A high water table may destabilise your pool and action must be taken to combat this problem.

What about the ground you will be digging into – is it rock, is it clay, is it shale? The sub soil can greatly affect your construction costs.

Once armed with all the necessary information, you need to rough out plan and elevation sketches. Mountain Pools can supply you with a site survey checklist so nothing gets missed! If you don’t feel confident to carry out this stage yourself, then Mountain Pools can carry this out for you for a fixed cost of £285 inc VAT (+ Travel).


The initial design stage is best carried out in-situ with either ropes or hoses. You can sketch on paper but it is much easier to feel proportion when you work full size. Think about where you would want to enter the pool, where you may want a waterfall, can you make use of the shape and slope on the site? Unlike swimming pools, pond liners are quite slippery so your design should include flat shallow areas and flat deep areas. The transition between them should be quite steep. A shallow transition means individuals may try to walk on the slope and could slip. Deep areas should be a minimum of 2 metres deep to allow for shallow diving. The design should also ensure that diving isn’t possible in the shallow areas. You may want to go deeper but remember, the more water you have the more you need to pump. The pond can be any size and the larger it is the easier it is to achieve a natural ecological balance. The minimum is 40-45m2 but remember half the area should be devoted the regeneration zone. Water always settles level so the site for the pool (after excavation) must also be level. Allowances must be made for run off of excess rain water. Water must not be allowed to flow into the pool from the surrounding area as this can bring impurities into your balanced eco system. Clean rain water can be used for topping up the pool caused by evaporation but all water to be used must be checked for pH levels. The site will need both electricity and water supplies. Don’t forget water and electricity don’t mix.

When you are happy with the plan, transfer the design to paper. A sketch showing the layout including depths, distances to other points in the garden such as boundaries and buildings, position of electrical and water supplies, should be prepared. Also include a sketch showing height variation across the site. Armed with this information, Mountain Pools can discuss any further design features you may require. We then calculate head heights, pipe losses, pond volumes, pump and filter capacities, liner sizes etc. This allows us to match specific components and filter media. You will then receive an itemised list of parts and materials with a quotation so you know just how much it’s going to cost.

Component selection

This is where we do a lot of the hard work for you. We only stock the best quality parts and we match components to suit you installation. Along with your mountain pool kit will be a detailed installation manual so you are left in no doubts of what goes where. And should you have any queries, Mountain Pools gives free advice and consultancy to all of its customers – you can talk to us as often as you need. Site visits can also be arranged if required.

Excavation and construction

Now is the time to mark out and excavate to the required depth. Make sure the finished shape is well compacted and all excavations for pump housings, skimmers, additional biofilters, pipe runs etc are completed. Any sharp protrusions must be removed and surfaces blinded with sand. You will also want a locking trench around the pool. This needs to be 250cm above the water level and about 250mm across by 250mm deep. This trench will be filled when the liner has been fitted to lock it in place. If required, a footing should be dug for supporting the wall between the swimming and regeneration zones. The construction of this wall can vary. It can be constructed from concrete filled hollow blocks or be simply an earth wall. This does require additional space as the wall will need to be much wider at its base to give reasonable support. Purpose designed plastic panels that clip together to create the wall are also avaialable. These only require a raised wall base to suit the 1m high panels. Whichever system is used, the wall should finish 300mm below the water level. This is important as it allows the water to flow from the swimming zone to the regeneration zone.

Liner installation

Before lining the pond we need to install underlay beneath it for protection. Old carpet can be used for this function but compared to other costs, the cost of liner underlay is not expensive. Make sure you overlap each part and trim off prior to the locking trench.

Installing the liner is no easy task and we always recommend that customers attend our training day which covers liner installation in detail. If you need to cut the liner then you will need it welding back together. This is a specialised job and we can advise on installers in your area who can perform this for you. If you can install in one piece (which is usual for a small swimming pond) then there will be no need for on site welding. There will be folds and there will be creases and it is a matter of minimising the folds and reducing the creasing where it really matters. For example, creases and folds in the regeneration zone are not going show; similarly if there is a deck overhang then this will hide the liner. The liner will be very heavy so make sure you have plenty of helpers. Always start at the bottom of the pool and work out, smoothing out creases and making folds where necessary. When you’re happy, trim the liner just below the surface as it exits the locking trench and fill your trench with soil, compacting it down as you go. Care must be taken. Repairing leaks once the pool is filled with water can be expensive.


Now we move onto the plumbing. You will receive with your Mountain Pools kit a comprehensive instruction manual which will detail the method of installation. Electrical connections for pumps should be in waterproof areas and installed by a qualified electrician. The pipes which suck the filtered water from the regeneration zone should be wrapped in geotextile membrane prior to the filter medium being installed.

Regeneration zone filter

It is essential to understand that without an efficient filter the algae will takeover. The basic regeneration zone is created by filling the area with a material that will give plenty of surface area for micro organisms to live and multiply whilst giving the plants a medium to root into. Gravel is cheap but it is a compromise. Because of its smooth generally spherical surface it does not have a very large surface area. The gravel should not include limestone material as this will increase the pH and cause problems with algae. The stone (and the water) should be checked for its effect on the pH prior to usage. Anything over 7.5 - 8 and you will have a problem. Other materials such as expanded clay or pumice which offer much greater surface area for their size (and a neutral effect on pH) can increase the efficiency of the filter.

If space is restricted and 50% area for the regeneration zone is not practical, then it is quite easy to include a biofilter. This is a container which is plumbed into the system. The container is filled with a material that bacteria, once added can colonise, as the water is circulated through the filter, giving added filter capacity. For some applications we offer a a modular system which includes pumps and filters. This system reducese installation time and require much less regeneration zone.


Planting serves to functions. Firstly to take up the nutrients released by the bacteria and secondly to create the visual effect of a natural pond. Many plants are suitable and the design is up to your imagination. It always makes sense to use plants that are known to thrive in your area. Contact local aquatic plant nurseries at an early stage and explain what you are doing. Show them your design and ask for their recommendations. When the plants arrive, they should be planted in pockets of growing media within the regeneration zone filter. Do this before the water is in the swimming pond. As the plants settle in to their new home their roots will grow down into the filter medium. Here the roots release oxygen which the bacteria thrive on. In return the plant receives its nitrates from the bacteria.

natural swimming pool training