How To Install RHS Slate Collection

Learn how to install the RHS Slate Collection in your garden design or landscaping project. This guide provides all the need to know information for installing the window stone water feature, slate bench and stepping stones.

Water Feature

The RHS Window Stone is designed as a stand alone water feature, with mains electric the only external supply required. The reservoir needs filling to begin and will require topping up through the seasons, particularly on hot summer days.

  1. Dig a hole approximately 1000mm (1 metre) in diameter and 310mm deep.
  2. Install the reservoir and fill with water.
  3. Run your mains electric connection and connect to the pump.
  4. Install the hose in the window stone.
  5. Carefully place window stone on the reservoir. This is best done with two people.
  6. Connect pump to hose and secure with hose clip provided.
  7. Optionally – Connect flow valve regulator (tap) to the hose and secure with 2 x hose clips provided.
  8. Turn on to see the window transformed into a water fountain.
  9. Adjust tap accordingly to the flow required.

Slate Bench

The RHS Slate Bench consists of three separate stones, namely two leg blocks and the thinner, wider top. The bases of the legs are sawn flat, top and bottom for stability and they are suitable for setting with a fixed concrete base. The measurement between the inside of each leg should be approximately 500mm. Use a spirit level to ensure the blocks are level and carefully place the top over the two blocks. There is no front and back to the blocks, simply choose the face you prefer as the front.

Stepping Stones

RHS Stepping Stones can be installed in a number of ways to suit any garden design or landscaping requirements. The easiest method is to simply lay the stones on the ground where required. The stepping stones are reasonably heavy but they are likely to move underfoot over time with this method. This simple method can work well in a gravel area where there is deep aggregate coverage. A slightly better practice method would be to dig shallow circular holes, 300mm in diameter, and lay the stepping stones on a few dabs of mortar.

We recommend the method of digging shallow circular holes slightly wider and deeper than than the actual stones, approximately 320mm wide and 40mm deep. Fill the holes with mortar, lay the stepping stone and gently tap with a paving mallet. Bank the mortar up around the edges of the stepping stone. This method provides the safest and most secure way to lay stepping stones, and the recessed depth means if installed in a lawn it’s possible to mow over the stones without causing damage.

Winter & Frost Advice

Our natural stone water features require very little maintenance other than occasional topping up of water. During the winter months there are a small number of tasks to keep your water feature in tip top working order.


The only element that holds water in our designs is the reservoir which stores and recycles the water. The reservoirs are usually dug down into the ground, they are not prone to freezing or splitting so the water can remain inside and does not need to be drained down.


The pump can easily be removed from the reservoir via the hatch and stored indoors over the winter. Always ensure all power is switched off before accessing the reservoir. When temperatures warm up and spring nears, the pump can simply be placed back in the pump and connected up again.

Hoses & Clips

Connecting the pump in spring is a good opportunity to check the hose and clips. If the clips are not able to be tightened completely they may need replacing, although stainless steel hose clips should not rust. Hoses can perish over time and even though robust, they can split in particularly low temperatures.


The water feature stones or slates do not trap or hold water as the water cascades downwards, so the only holding place for water is the reservoir. Welsh Slate is a very durable material. It can withstand fluctuations in temperature and remains constant.

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