A cracked pipe can send pond water into the ground instead of back to the feature. Damp soil near a buried line, water bubbling up while the pump runs, or a sudden drop in water level may be clues. They are not proof: splash, a low liner edge, and a loose fitting can produce similar symptoms. For the broader first check, see Is My Pond Losing Water to Evaporation or a Leak?.
Make the feature safe first
If the water level is falling quickly, stop the affected pump according to its instructions so it does not run dry. Turn off power before handling the pump or reaching near electrical equipment. If water threatens a building, electrical installation, or unstable ground, contact a qualified professional promptly.
Trace the likely route
Note where the ground is wet, whether the spot changes with the pump on or off, and which pipe carries water through that area. Look at accessible fittings and connections before assuming the buried pipe itself has cracked. Mark the suspect area and photograph it. Do not dig until you know where electrical lines, plumbing, and other buried services are located and have followed local requirements for locating them.
Confirm the damaged material
Once the line is safely exposed by someone equipped to do so, inspect the full damaged section and identify the pipe material, diameter, and fittings. A repair method for rigid PVC may not work for flexible pipe or a specialty connection. Use compatible replacement components and follow the pipe, primer, cement, and fitting manufacturers' instructions, including preparation and cure time. Do not restart the pump before those directions permit it.
Test before covering the line
After a repair, check that the line is supported and that water flows normally without seepage at the repair or nearby joints. Monitor the water level and the ground before restoring the surrounding area. If the cause was freezing, settling, or repeated stress, correcting the damaged piece without addressing that cause may lead to another leak. For a different edge-related problem, read How to Check a Low Pond Liner Edge for Leaks.