Water and sewage treatment cost money.
you reduce water consumption, you can save on both counts. If you have
an older water-guzzling toilet and it starts to need repairs, give
serious thought to replacing it entirely.
of spending money on what will probably be a continuous string of
repairs, invest wisely and get a reliable fixture that will save you
money over the long run.
This is also true for faucets and shower heads. Anytime these need attention, consider replacing them with new, water-saving units.
When the water heater getting old, consider to replace with another water heater or with a tank less, but you must follow the manufacturer recommendation.
If you forgot to clean your main line and the clean out is inside the basement with a 3 inch size, is better consider to install 6 inch outside clean out for a better cleaning. By the way the main sewer line is 6 inch size.
And don't forget something: do not listen your neighbor. He is not a licenses plumber!