Garden Waterfall

by Mike Gilmore

Garden Waterfall DesignThis garden waterfall evolved as a result of discovering large pieces of blue slate in the garden. With a great deal of hindsight, I now believe the existing curved slate waterfall was once part of a short curved slate garden staircase (which must have been lethal in the wet).

Pictured left; the site of the proposed garden waterfall during initial clearance. Originally I’d been told by the previous owners that it was just 4ft deep. By this point I’d stopped clearing the concrete blocks out because of the high risk of one falling back upon me! Eventually a backactor (JCB) excavated to the original Victorian brick-lined base at 10ft. Today, this cistern is just part of the garden’s irrigation system as described in Garden Irrigation.

Garden waterfall slateUnfortunately, the slate was not discovered in a single location at the same time but rather piecemeal over several months as various parts of the overgrown garden were discovered and cleared.

Pictured left, the 8ft wide garden waterfall after initial construction, which reproduces the original garden staircase. The upper two slates are triangular. Behind the uppermost slate is a triangular concrete ‘header tank’ formed against the garden wall. This tank collected the water from the circulatory pump outlet, and a system of baffles inside it ‘pacified’ the tremendous water flow from the 2000 gall/hr swimming pool pump enabling the water to exit evenly across the top slate. The high water flow was chosen because:

  1. A flowing curtain of water over the edge which requires about 300 galls/hr per linear foot.
  2. The larger pump capacity could be used to provide a pumped irrigation system at some future point.
  3. Fire safety. Due to the garden’s isolated country location, the pump can supply water in the event of a domestic fire within a tenth of the time it takes the fire service.

The picture above shows the maximum water level after the first fill. This is because of a leak running right around the tank at this level. The tank was subsequently drained and resealed with waterproof cement see concrete water tank repairs.

Garden waterfall over blue slate 8 feet wideThe cascading waterfall (pictured left) worked well and proved a popular feature. However, since the cistern was used for irrigation and as the resulting water level dropped significantly during the summer months, the resulting noise from the plunging torrent proved deafening.

Later, a second much smaller pump (100W compared with the 2kW of the swimming pool pump) provided the waterfall effect at a gentle trickle allowing visitors to sit nearby, and hear themselves think.

During the first weeks of summer following its completion the area was a fertile breeding ground for mosquitoes and midges. Within ten days of adding Golden Orfe to eat the larvae the insect problem was eradicated. The fish also provide an additional welcome focal point in the unfiltered water. (Unfiltered due to the constantly fluctuating water level).

Trickling water is much more relaxing than raging torrents!Nowadays, the trickling sound of the water is more weir-like and gently soothing along the entire 8ft of the cascade. The small pump still covers the width of the slate and we still have the option to use the bigger pump when we need to irrigate via the take-offs described on the irrigation page.

An adjacent fern garden (under bamboo) provides a contemplative area in which to sit and view the flower borders beyond.

Cement pond repairs: Click here