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Irrigation for Tennis Courts

Irrigating Lawn Tennis Courts

The irrigation of Lawn-Tennis courts is important; it helps playability and prevents injuries to players. Turf courts require irrigation to keep the turf at its best during the drier months. Irrigation helps keep the turf strong and vigorous. It allows the turf to utilise those fertilizers you have spent good time & money on applying. The likes of Wimbeldon courts are all irrigated with hidden automatic pop-up sprinklers that have been installed below the surface.

If you want to optimise results (i.e. create a consistent surface across the entire area, without some areas being too soft or other areas being too hard) then the irrigation system must be fit for purpose. Sprinklers that are too small will only cause more problems than benefits for the reasons mentioned above, since they won’t be able to irrigate the entire surface uniformly enough.

Rotors operating
If you are going to include the additional areas around the perimeter of any given tennis court; behind the actual court and to each side, then this means the court is around 18.3 metres wide x 36.6 metres long. Each end of the court (from the net) is therefore a square; 18.3 metres wide x 18.3 metres long.
It is important with irrigation sprinklers to treat the court as 2 halves, because the net will get in the way of any irrigation system that doesn’t account for it. If you ignore the net then the sprinklers will make a mess when they hit the net, and big wet areas will develop under the net.

Treating each end of the court as a square makes irrigation-life significantly simpler. All we need is a professional sprinkler that will throw the water from one side of the court to the other as evenly as possible. Therefore a sprinkler that will throw the water approx. 18.5-19 metres is perfect. To maximise uniformity of irrigation-coverage we have sprinklers at each corner of the “square”, each throwing over the others in a quarter-circle arc. This might seem like a waste to a novice, but sprinklers do not throw an even amount of water across their distance; the water landing on the surface reduces as we get further from the sprinkler. Therefore we have a second sprinkler in the opposite corner throwing back across, and the 2 sprinklers covering any given area will create a very uniform coverage in terms of mm of water landing on the surface. So at each end (from the net) of the court we will have 4 sprinklers; one at each far corner of the court, one at the net throwing back over the court, and the 4th one at the other side of the court, at the net, also throwing back over the court.

This 4-sprinkler configuration is repeated at the other end of the court. Incidentally this means that at the net there are 2 sprinklers that are almost beside each other on either side of the court (i.e. 2 at where the umpire’s box would stand, and 2 on the opposite side of the court behind where the net-ball boy would crouch. With each of these pairs, one is throwing to one end of the court and the other is throwing to the other end, and neither is wetting the actual net! This means there are 8 sprinklers covering the overall court. Each sprinkler will throw 18.3 metres radius across the court and each sprinkler will be set to irrigate only a quarter-circle of area.

Tennis court dimensions with sprinkler placement

Tennis court dimensions with sprinkler placement

We suggest the Rainbird Eagle 751E; this is a professional sports turf sprinkler that is buried such that its top is flush with the soil surface. When it is turned on, it’s internal assembly pops up 4” above the ground and sends water out through its nozzles. As soon as the water pressure is stopped, its internal springs pull it back down under the ground.

Each sprinkler has its own inbuilt “tap” built into it. This is called “electric valve-in-head” and means the sprinkler has its own low voltage solenoid valve built into it. This means we don’t need to install anything but the actual sprinkler (which is almost invisible from the surface) plus the buried irrigation pipes, and a buried low voltage solenoid cables. This makes the entire system almost invisible.

If you have turf on your court then you can opt for a sprinkler with a sod-cup on its top; this means that when the sprinkler is not in use it is almost perfectly invisible.

Sod Cup hidingSod Cup operating

Your Water Supply:

These sprinklers, and any large professional sports turf sprinkler on the market, require a pump to make them operate. Regardless of how outstanding you believe your watermains pressure is, I can guarantee it will not be enough. Incidentally it is illegal to operate these sprinklers directly off your watermains because of backflow prevention, which means that the watermains provider does not want the potential of your “used” water getting sucked back into their pipes if anything goes wrong. Therefore we need to ensure your irrigation system includes a water storage tank and an irrigation pump. This can be installed around the rear of your buildings. Your watermains water can be used to fill the water storage tanks as long as it is done by a qualified plumber and includes an “air-gap” to prevent backflow. To apply 4mm of water daily to your tennis court (keeping up with the maximum average evapo-transpiration rate in mid-summer) a 3,000 litre tank will hold enough water for one day’s worth of irrigation. A 10,000 litre water storage tank therefore would allow for 3 days’ worth and gives you plenty “up your sleeve”. A enclosed polypropylene tank is safe and won’t break your bank.

The irrigation pump needs to be big enough to do the job. To operate even 1 of the Rainbird sprinklers mentioned above, on its own, your irrigation pump will need to deliver no less than about 1.3 litres per second flow rate (4.9 cubic metres per hour;20 gallons per minute) at no less than 4 bars water pressure (400kPa; 60psi). This is quite an ask and is well outside the scope of any domestic pump. Normally an irrigation pump that will deliver this will require around 2 kilowatts of power. To operate 2 sprinklers at the same time you’ll therefore need no less than 2.6 litres per second flow rate at no less than 4 bar pressure. For more information on choosing the right pump, speak with your irrigation contractor or contact us.

Irrigation Pipes for your Tennis Court Irrigation System:

With the flow rates mentioned above, you are best to use no smaller than 63mm PE (polyethylene) irrigation pipes, installed preferably as a ring main around the perimeter of the tennis court. This pipe should be black, not blue, to differentiate it from watermains pipe.

Making it Automatic:

Making an irrigation system automatic (using an automatic irrigation controller) has many advantages. Irrigation can be timed to come on at night time when it will not interfere with play. It means that your turf can have all night to recover from a dry day. You can apply the water in several small bursts to let it soak in, or you can flood the court… it’s your choice. Even if you don’t want to leave the irrigation in the hands of the Gods, you can use an irrigation timer to apply a certain number of minutes onto the court from each sprinkler, using a semi-automatic function (you turn the sequence on, then it will irrigate all the sprinklers, one at a time). This maintains uniformity by ensuring each sprinkler operates for the same amount of time as all the others; thus applying the same amount of precipitation across the entire tennis court surface.

Automating an irrigation system is a comparatively low cost if you have opted for the Rainbird Eagle 751E sprinklers mentioned above. Less than £200 will get you a good little Rainbird automatic irrigation controller that will allow irrigation to happen at any time, day or night; it can irrigate every night, or every second night, or 4 times a night! It can make each sprinkler irrigate, one after the other, to get through the entire 8 sprinklers while you sleep! You can alter how long each sprinkler operates.

Importantly, you can also turn the automatic irrigation controller to the “OFF” position when people re playing or when the rain is offering enough water! Incidentally you can also have a rain sensor installed for a further £40 which will prevent the irrigation system from operating if there has been enough rain. This is also an automatic function once installed.

Manual Watering Points:

With any automatic irrigation system it is handy to have at least one manual watering point at each end of the court. This is beneficial for spot-watering and for repairing odd spots. A quick coupling valve can be installed into the irrigation mainline mentioned above, and this can be used to connect your hose to. This is worth its weight in gold for anyone looking after a tennis court.

Your Next Step:
Contact us. We can either visit you to discuss options in more detail, or we can put you onto a reputable contractor who would be able to supply & install an irrigation system.

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