Stormwater drains are the drains which funnel away rainwater from your downpipes and grates. They are just as susceptible to tree roots and being dislocated by earth movement as sewer lines, though blockages in them aren’t as noticeable.
Unlike sewer lines, you don’t have blocked toilets and drains in your house to signal a serious blockage. Instead, the only give away may be in a heavy rain storm when your drains struggle to cope, amounting in a pool of water that could run back into your home.
Stormwater drains need maintenance too. Having a high pressure water jetter or a sewer camera run down your stormwater line is a common service that most plumbers can provide for you. This will allow you to see if there are any problems (was the pipe crushed when your house was renovated a couple months ago? Did that big tree in your front yard get into the subterranean pipes again?) and allow the plumber to provide you with his best recommendations.
Peace of mind is never a bad thing, especially when you can curl up inside and watch the rain, knowing that none of it will be flooding back into your home.