Have you ever noticed your swimming pool loses more water during the day while the pump is running, but seems to hold water better at night when the system is off? You’re not imagining things and are likely dealing with a leak in your pool’s plumbing lines, equipment, or return fittings.
Let’s break down exactly why this happens and what it means.
1. Leaks on the Pressure Side
Water is pushed through the return lines under pressure when your pool equipment is running. If there’s a break, crack, or loose connection on any of these pressure-side plumbing lines, which run from the filter back to the pool, it will leak much more when the system is on.
Signs of a pressure-side leak include:
- Water loss increases while the pump is running
- Wet spots around the return plumbing or near the equipment pad
- Air bubbles in the return jets (less common than on the suction side)
These leaks might be completely inactive when the pump is off, only appearing when water is pushed through the lines.
2. Equipment Leaks
Pool pumps, filters, heaters, chlorinators, and even valves can all develop leaks, especially when under pressure. Running water magnifies even the smallest seals, unions, and pipe fittings failures. This is why a leak at your pump or filter may only be visible when the pump is running.
Look for:
- Drips or puddles on the equipment pad
- Water spraying from valves, PVC plumbing joints, or compression fittings
- Corrosion or scale buildup around connections
3. Return Fitting or Jet Leaks
Another common weak spot is where your pool jets enter the concrete pool wall. If there’s a crack in the fitting or the pipe connected behind the wall, water will oftentimes escape only when water is actively flowing through the return line, again, only while the pool is running.
These are difficult to spot from the surface. Still, a leak detection specialist can do a dye test, pressure test, or use their professional audio equipment to pinpoint the exact problem.
So, Why More Water Loss When It's Running?
Because pressure changes everything. Plumbing and fittings that might not leak when static can leak rapidly when water is forced through under pressure. If your pool holds steady overnight but drops quickly during the day, it’s almost always a pressure-side leak—not evaporation or a crack in the pool shell.
Don't Let It Keep Draining
Water loss isn’t just a nuisance—it can lead to costly damage. Don’t ignore it if you notice your pool losing water only when the system is running.
Call Precision Leak Detection, based in Jupiter, Florida. We specialize in finding and diagnosing pressure-side plumbing leaks and other hard-to-find swimming pool leaks. Let us help you get your pool sealed up and running correctly again.
