A collapsed sewer line is a severe problem, so you’d spot one right away if it were to happen, right?

Well, maybe not.

Sometimes, collapsed sewer lines have symptoms that don’t make sense to homeowners. You may be expecting a sudden gush of water on your lawn or the street, but that’s not always how sewer line collapses manifest. Here are six signs of a collapsed sewer line that you should know.

1. Multiple Clogged Fixtures

When one sink or tub clogs, the problem is usually local. That is, the problem is usually right in that individual fixture’s own drain line. However, when multiple fixtures are clogged, it’s unlikely that they all have their own clog. Instead, they likely have a shared clog further in the system. A collapsed sewer line can cause such a clog.

2. Multiple Back-ups

Back-ups are when water pours out the drain into the fixture it is supposed to drain. You might notice water pouring into your bathtub or your utility sink in your laundry room. Less commonly, kitchen sinks and bathrooms sinks can suffer a backup too. When multiple fixtures are suffering from a back-up, the cause is usually a collapsed sewer line. One backup might be an early sign of sewer issues too.

Slow drainage, while not quite a backup, can also be a sign of a collapsed sewer line. Again, the more fixtures that are affected, the more likely it’s a sewer collapse causing the problem. Even a few moments of back up, on a few fixtures, could be the result of a sewer collapse.

3. Unusual Sounds

When the sewer has collapsed, air can get into your plumbing system from the reverse. This can cause some unusual noises, such as gurgling. You might hear gurgling in the pipes, or in the toilet when it flushes, or in the drain after the water goes down. In this case, re-piping may be the best solution.

4. Sewer Smells, Inside or Outside

Of course, sewer smells, especially strong ones, may be a sign of sewer collapse. You may smell them inside, as the air from the sewer rushes back up the pipes. Or, you may smell it outside, closer to where the sewer collapse actually is.

5. Trees and Grass Growing Too Well

The only thing a sewer collapse is good for is plants. The water in your sewers is a great food for them, so if it collapses and spills out, even below ground, plants may do very well. You may notice a tree or two seems much healthier than normal. In fact, tree roots breaking into the sewer line may be the cause of a complete sewer collapse.

Or, if you have a sewer leak, you may notice that your grass may need to be cut much more often. That’s because the grass is enjoying the extra water and nutrients from the ground and is growing faster. However, these underground leaks can cost you a fortune, and be a big problem, so it’s wise to get them fixed right away.

6. Water Sitting on the Lawn

Sometimes sewer collapse does cause the obvious, dramatic water on the lawn that you’re expecting. Sudden swells of water, or constant soaking, may also be signs of a collapsed sewer.