Most good new toilet will recommend replacing a gate valve regardless of its condition. The time to discover if it will work is not during a flood in your bathroom. If you have it replaced with a ball valve then check your water heater and laundry valves, too. Have them replaced at the same time with premium ball valves. Ball valve laundry bibbs make it easy to shut off the water to the washer after each use which may help to prevent floods in the future.
The repair of a ballcock tube is the simplest repair of all toilet leaks. There is a small black tube that is in the tank of the toilet that connects to the flush valve fill tube. If the tube slips from the little clasp that holds it in place, it can begin spraying water line repair in the tank and out from under the tank cover. To fix this toilet leak, simple re-attach the black tube to the clip. It really is that simple.
If you need to add copper pipe make sure that you clean the old and new pipe by using sandpaper, inside and out. If it's not clean the solder will not flow into the joint. Another tip is to not over wrap the mail threaded pipe with tape, this can cause a leak. Twice around should be enough. Also, don't over tighten it.
Sales representatives must know beforehand that almost all the answers above need to be encouraging. Otherwise, there is a slim to none chance a sale is made. Besides cold call prospecting, so much of the typical sales rep's time is spent trying to make sales when a sales situation does not truly exist.
Be certain that the bathroom exhaust fan vents to the outdoors, not into the house or attic. If the exterior vent dampers don't operate properly or water line repair don't seat well have them fixed or replaced.
And the way to know what's sufficient? Well, until the work is done an the bill paid you won't know for certain, but this is the best that can be suggested and normally works very well.
Over the counter drain cleaning products offer convenience and effective results. However, they are best left to those who need to simply improve the flow of water, not those who need to repair it.