What is a water sump pump and how to build a surface drainage sump pit.
A 'sump pump,' is a submersible pump with a built in float switch that automatically cuts the power to the pump when there is no water left to pump . The pump is used for draining surface water that is being drained into a sump pit because the French drain drainage system cannot be connected to the surface water drain in the usual way. The pump should always be able to pump dirty water - this means water containing grit, sand, mud and small pebbles.
A sump pit is the hole in your garden or lawn surface water will collect in, before being pumped away. Building instructions for a basic sump pit are at the bottom of this page.
Instructions to install French drains and Mike's contact details can be found on lawn and garden drainage page
A drainage sump pit.
A sump pit is normally found in the basement of buildings/houses to drain the excess water in the area under the footings. The sump collects water flowing in during storm flooding, as well as water rising up from a saturated ground supply. It's simply a concrete lined hole in which water collects from ground water if the basement is below the level of the water table. It also collects rainwater.
Sumps are also used with garden surface drainage and French drainage systems when the rainwater cannot be drained into the surface water system.
The water which collects in the sump has to be pumped out from time to time and this is where the sump pump comes as it is needed to pump the water from the garden drainage sump into the surface water drain.
It's always best to fit a submersible sump pump with a controller, normally a plastic or rubber floater that automatically switches on and off as the water rises and falls. It's also a good idea to fit a strong removable cover over the sump pit for easy access to the sump pump and to stop the kids falling into the sump.
You will also need to connect a hose to the pump to pump the rainwater into the surface drainage system. The sump pump hose can be run over the top of the lawn or garden to connect into the surface water drainage system but can be a nusance when mowing the lawn or even a hazzard for kids playing on the lawn. The pump hose is best burried under the garden or lawn.
Most garden drainage sump pumps come with at least a couple of metres of electrical cable and a qualified electrician will need to be hired to make the connection.
Technical stuff when purchasing a surface drainage sump pump.
Head and Flow Rate
The ability of a pump to pump is shown by itshead and flow rate. The head is the maximum height to which a pump can pump water. In the UK most pumps are sold with the head specified in metres or feet.
When selecting a pump you need to measure the height difference between the sump and the point the water is to be pumped too. The head of the pump must be at least 25% greater than that measured distance.
A check valve will need to be fitted as this allows water to flow up and out through the pipes. And when the pump turns off the check valve stops the water in the pipes flowing back into the sump.
The flow rate is a measure of the amount of water which can be pumped by the pump. This flow rate falls when water is pumped upwards.
Price guide for garden drainage pumps
High Flow Sump Drainage Pumps
Submersible sump pump made of stainless steel, with a float switch, Suitable for draining a garden sump of dirty water with a 1.5" Outlet, 230V, 10mm max solids,
will cost from about £560
Medium Flow Sump Drainage Pumps
Submersible pump for sump drainage.complete with float switch. Suitable for pumping dirty water with 1.25" Outlet, 230V and handling 10mm max solids
will cost from about £160
If you are into DIY make sure the pump you purchase is made for the job. Make sure it switches on and off auromatically and can pump water over the distance from the sump pit to the surface water drain.
How to build and install a sump pit for draining a waterlogged garden.
If you have a waterlogged garden or lawn, as described on my garden drainage page and can't drain the water into the surface drainage system because the garden slopes away from the house, a sump pump combined with a French drainage system is your best option. These systems are cost effective, low maintenance and activate automatically to remove the water.
You will need: a spade, wood, cement, spirit level and a tape measure.
Work out the best place to dig the sump pit. This will be the lowest point of your garden or lawn and always where the surface water puddles. Remember you are connecting French drains and water will not travel uphill.
Dig the sump pit 27 to 36 inches deep and 24 inches square to allow for the concrete lining. Check the sides are smooth and free from rocks or roots and the bottom is level.
Build a wooden frame to fit inside the pit. Pour in concrete to form the walls of the garden drainage sump, allowing at least 3 inches on all four sides. The top should be level with the lawn or a couple of inches below if you want to hide the lid under decorative gravel. Add a small strip of 1-inch wood to the top edge of the frame. When the concrete dries this will form a lip around the top of the sump pit to support the cover.
Mix the cement, following the manufactures instruction for a fairly thick mix. Now pour the concrete around the outside edges until it is flush with the lawn, then pack it down, remembering to add any additional amount needed and smooth it out. Allow the concrete to set for a minimum of 24 hours and then remove the frame.
Fill the bottom 4" with at least 20m gravel. Pea gravel could block the sump pump.
Fit the sump cover.
For lawn care,Mowers,Aerators,Scarifiers,Lawn edging, lawn tools and grass seed Visit the lawn care shop
Soggy compacted lawn tip Use your hollow-tine aerator to spike soggy patches then brush grit sand over the area working into the holes to improve condition and help surface drainage.