We have a recurring problem here at Place IV… FOG Clog. FOG in this case means Fats, Oil and Grease. A pain in the drain. A costly pain.
Fats, oil and grease should never go down ANY drain. Examples are:
Bacon grease, cooking oils, shortening, lard, sauces, meats, grease and fat from cooking. They cool and solidify on the way down, clinging to the sides of the drain pipe and cause extreme narrowing of the pipe (see the picture below — this is real!)
Other items clog our pipes, such as:
Cat litter, cotton swabs, dental floss, sanitary products, paper towels, condoms and “flushable wipes” … These all contribute to clogging our drain pipes.
NEVER pour any of these down the drain (or even flush them down the toilet) – they cool in the pipe, harden and eventually cause blockage. 
These clogs have flooded some units when the water from above has nowhere to go but back up. Please, let your grease cool, scrape it or pour it into paper towels (or something absorbent) and dispose in your regular garbage. Please, avoid the convenience of pouring ANY OILS in the sink or the toilet or disposing any of the listed items down the toilet.
Last year we paid over $30,000 unclogging pipes from obstructions. That is a cost that we ALL SHARE. We would like to keep our (your) condo fees down as much as possible – your assistance will help.