Plumbing repairs take time and money, which is why many homeowners choose to handle some plumbing issues on their own. However, one of the most common mistakes DIYers make is over-tightening faucet supply tubes, pipes, plastic fittings, and bolts that hold down toilets or fixtures. They think that the tighter it is, the better, but that is often not the case. Over-tightening can cause fittings to split, crack, or break altogether, which can also cause a leak. And the worst part of this small error is, it could take weeks for a fitting to completely break, and by then you could be dealing with a leak that could cause major flooding.
Likewise, under-tightening can also cause leaks. Check your fixtures and fittings often to see if they were looser than when you installed them.