Toilet Rough-In
Plumbers Picks Toilets Part 1: Toilet Rough-In and Flushing System


When choosing a proper toilet, there are several factors to consider. Unfortunately, not much attention is given to toilets until they need to be fixed or replaced. The toilet’s rough-in and flushing system are two critical factors to consider when choosing a toilet. The professionals at Ray May Plumbing are ready to help you make the right choice.

In this first part of a multi-part series, we address the rough-in and the flushing system of toilets.

The Toilet Rough-In

  • Rough-in refers to the distance from the wall behind the water closet to where it bolts to the closet flange on the floor.
  • This measurement is obtained by measuring the distance from the wall, not the baseboard, behind your toilet to the bolt caps of the current toilet.
  • The standard measurement is 12″. There are also 10″ and 14,” but these are less common.
  • It is vital to have this information to make sure that your new toilet fits in the preexisting space.

3 Types of Toilet Flushing Systems

  1. Gravity-Fed
    • The gravity-fed flush occurs in flapper or canister-type flush valves. When the trip lever is depressed, the flapper or canister lifts, allowing the water to drain from the tank into the bowl. At the same time, a vacuum seal is broken, causing the water in the bowl to evacuate into the waste piping.
  2. Pressure-Assisted
    • Pressure-Assisted toilets use a sealed, pressurized bladder that allows pressure from compressed air to force the water from the bowl down the waste pipe.
    • Tend to generate a stronger flush than gravity-fed toilets.
    • The drawback to pressure-assisted toilets is the noise. Pressure-assisted toilets create more noise than their counterparts.
    • The solution to the noise created by a pressure-assisted flush would be a 3″ flush valve.
      • An industry standard for the opening between the tank and bowl is 2″.
      • Many toilet manufacturers offer a 3″ flush valve, which increases the opening by 1″.
      • This, in turn, makes the toilet flush more thoroughly without the loud sound made by pressure-assisted toilets.
  3. Dual-Flushing System
    • For those wishing to conserve water, a dual-flushing system would be beneficial.
    • These toilets have two buttons on the top, each flushing a separate amount of water.
    • One button flushes a smaller amount of water for liquid waste, and the other flushes a more significant amount of water for solid waste.

We welcome you to visit our showroom located in Montclair to check out what we have to help you with your plumbing needs. 

Check back soon for more plumbing information. Thanks!