Birdbaths, depressions, or low areas on tennis courts are commonly defined as a low spot on the court that holds water. According to the ASBA (www.sportsbuilders.org), a birdbath is any area that water gathers and is held in a volume higher than 1/16” (2mm or the width of a nickel) for longer than an hour of drying in 70 degree Fahrenheit.

Depending on the severity of these areas, they could lead to delayed play and in the longer run mold or algae. The mold is a greater concern as it can either make play unsafe due to slick conditions, and even delaminate the acrylic on the surface. It is generally recommended to keep any court clean of such growth; power washing the courts is an effective action for mold removal.

These depressions could also be a result from improper construction or base preparation. Meaning that the courts could have been constructed using an improper slope, organic materials in the subsoil, improper compaction of the sub grade, or even bad drainage around the site. Over enough time most courts “settle” even with a perfect installation because of materials in the subgrade or site drainage issues.

There are 3 ready solutions for birdbaths, and they range in application and price. The cheapest option would be to apply multiple coats of an acrylic patch mix, once built up and flush with the surrounding areas and sanded smooth the courts could be painted. Next, you could tear out the court, or re-mill the asphalt giving a new surface. One of the most effective options would be to employ a modern day synthetic overlay system; they range in style, cost, and construction, but may also be the most cost effective. Depending on the court and its condition.