A Wet Spot in the Lawn That Won't Dry

A patch of lawn that stays soggy, sinks under your foot, or grows greener than everything around it is telling you water is coming from below. There are only a few usual suspects, and you can rule most of them in or out yourself.

Where is the spot?

• Between the meter box and the house, roughly in line with where the water enters: points to the service line.
• Near sprinkler heads or along a straight line between them: points to a sprinkler lateral.
• Near a valve box: a zone valve or the mainline.
• Near a downspout or at the low corner of the yard: possibly runoff.
• Over the sewer line route, often toward the street from a bathroom side of the house, especially with an odor: a drain line, which is a different problem.

The meter tells you a lot

With every fixture and the irrigation off, watch the meter. Moving, and still moving with the house shutoff closed: the leak is on your side of the meter in the buried line. The check, whose line it is.

If the meter is still and the spot is still wet, it's probably not the household supply. On pressure irrigation, a leak wouldn't show on the meter at all.

Run the sprinklers zone by zone

If the spot gets wetter during one zone, that zone is the likely cause. If it's wet even with everything off, the mainline or the service line is more likely.

Smell and color

A sewage smell, or greasy, discolored water, points to a drain line. Clear water with no smell points to supply or irrigation.

Why the wet spot can be in the wrong place

Water follows the easiest path, and the loose fill of an old trench is a highway. It can surface several feet from the actual leak, and on a slope, well downhill. That's why digging at the wettest spot is sometimes a miss and why a locate pays off.

What to do now

• If water is coming up fast, close the house shutoff.
• If it's on the street side of the meter box, call Veolia.
• Photograph it daily for a few days, with the meter readings.