The answer may surprise you. It turns out that, for the most part, toilet paper is designed to break down in the water. This means that, in most cases, it won’t cause problems when flushed.
But, there are some exceptions. Some types of toilet paper are made with synthetic materials that don’t break down as easily. Properties with old-fashioned septic systems usually can’t handle toilet paper, either.
Also, if a large amount of toilet paper is flushed at once, it can cause a clog. So, it’s generally best to err on the side of caution and dispose in the trash (if you can) instead of flushing it down the toilet.