Two types of rats are found in the United States: Norway and roof. Burrows in the ground are a good indication of Norway rats. These rats are about 16 inches in length, including the tail, and greyish-brown in colour. Pet and laboratory rats are a variety of Norway rats. Roof rats are darker in colour and better climbers, so they typically nest above the ground. You can use flooding to get rid of a rat burrow, but there are some things you need to consider before you do it.
About Rat Burrows
Norway rat burrows can be found almost anywhere. Their entrances are about 2- to 4-inches wide and free of dirt or debris. There is no mound although dirt may be packed around the entrance. Rats often have multiple nest sites, moving randomly between them. To see if the burrow is currently occupied, fill it with newspaper. If the hole is cleared within a few days, rats are using it.
Flooding a nest has its problems. Norway rats typically have several entrances to their nests. This means the flooding may not drown them but simply flush them out. You'll need some method of eliminating the rats when they emerge, or you'll continue to have a problem. Flooding should not be used on burrows near homes or buildings because it can damage the foundation or flood the basement.
Flooding should be done in the late winter or early spring before the rats start reproducing. According to Russell Link, an urban wildlife biologist and author of "Living with Wildlife in the Pacific Northwest," your garden hose will provide ample water to flush out the rats. Stick the hose into the entrance and turn it on full force. Watch the other entrances for rats to emerge. Kill any rats that emerge with a shovel. Once the rats are gone, fill in the holes with dirt.
Once you have dispatched the rats, take steps to prevent new rats from moving in. Pick up around fruit and nut trees. Feed pets inside or remove their dishes after feeding them. Secure trash in cans with tight-fitting lids. Add baffles to prevent rats from accessing any bird feeders. Clean up any brush or trash piles that provide cover for rats.