Abstract: An underground watering system for an athletic facility such as a tennis court, comprising a plurality of select equally spaced shallow water reservoir trenches having rounded surfaces over which is applied a waterproof liner. A water distribution pipe is located on the lining at the bottom of such trench and extends the entire length thereof. The trenches are filled with fine stone aggregate over which is laid a water permeable fabric which covers the whole area to be watered. A relatively coarse layer of aggregate is placed over the fabric followed by an upper layer of relatively fine aggregate. A layer of playing surface material overlays the fine aggregate layer. Water supplied to the trenches via the distribution pipes will saturate the permeable fabric and will be drawn up to the playing surface by capillary action.