How Dual Flush Toilets Work

Installing a Dual Flush Toilet

The process of installing a dual flush toilet is similar to that of installing a low flow toilet. Although using a professional plumber is the easiest way to go, it's a job that a do-it-yourselfer can tackle in an afternoon.

If you're planning on doing the installation yourself, there are a few things to consider. The general suggestions below will give you an idea of what's involved, but dual flush toilet models differ, so pay close attention to the instructions that come with the dual flush toilet model you're considering:

  1. The standard rough-in measurement for a toilet is 12", but that can vary, so measure the distance from the wall behind the toilet to the center of the bolts affixing your toilet to the floor. You should also check the diameter and shape of the base of your toilet to make sure the replacement will cover the footprint your old toilet occupies. You'll need this information to select a replacement toilet.
  2. Turn off the water supply to the toilet.
  3. Remove water from the toilet by flushing it repeatedly. If there is any water left after flushing, try suctioning it up with a shop vacuum.
  4. To make it easier to remove the toilet, put plastic down along any carpeted hallways or rooms between you and the trash. A wheelbarrow or other aid may also help in getting the old toilet out of your home.
  5. Disconnect the toilet's supply hose.
  6. Disconnect the tank from the bowl. There are typically two bolts, one on either side of the toilet, that have to be removed.
  7. Unscrew the two bolts that attach the old toilet to the floor.
  8. Remove the old toilet.
  9. Place a rag in the floor drain temporarily to trap any gas that might escape from the drainpipe. Clean away any old wax.
  10. Install the wax seal or gasket of the new toilet according to the manufacturer's instructions. (Hardware and fittings are usually included with the toilet.)
  11. Install the offset collar/adapter of the new toilet to the closet flange, the fitting that connects to the drain line.
  12. Put the toilet in place. Install any necessary bolts.
  13. Install the rubber gasket on the outlet of the new water tank, and insert the screws and rubber washers. Attach the tank to the bowl by sliding the screws through the holes in the back of the bowl. Add the nuts and tighten them into place.
  14. Connect the supply hose. A new hose may be included in your toilet installation kit.
  15. Apply silicon seal around the base of the toilet. (A shim may be necessary if the toilet isn't level.)
  16. Reconnect the water line.
  17. Install the toilet seat.

If the prospect of installing an entirely new toilet doesn't appeal to you, there are retrofit kits available that will convert your existing toilet to a dual flush system. The bowl will still use a siphon system to evacuate waste, but you'll be able to conserve water by selecting which flush mode you want, partial flush or full flush.

Interested in the future of the U. S. toilet market? In the next section, we'll take a look where we're headed and what that might mean for dual flush technology.