#4 Banging or tapping sound when using the dishwasher?
Truthfully, pipes can make a myriad of very weird noises, and a lot of these sound quite spooky. Some of the ones that you hear with your dishwasher can also be heard after you flush the toilet! And both of those sounds indicate that there is a problem with the plumbing, which you should investigate as soon as possible.
If the tapping sounds are coming from the dishwasher, then it is probably caused by a clog in the draining system. The hog through which all the water from the machine drains out sometimes gets clogged with debris, and the rough flow of the water causes the tapping noises. If the banging is heard from a running sink or after flushing the toilet, then you may have a water hammer on your hands, meaning there is a lot of pressure in the pipes caused by excess water or air.
In both situations, you have to remedy the situation and get rid of the sounds as soon as possible. To get rid of the air pressure in the pipes, you could drain the system, which generally should do the job, while for the dishwasher, you have to get the drain hose cleaned. This can be quite tricky to DIY, so you should generally get a professional plumber to look at it instead of attempting it yourself.