Toilet Types – One Piece or Two Piece
All modern toilets either have their tank and bowl molded together as a single assembly (one piece toilet) or have a separate tank and bowl held together by long bolts (two piece toilet).  The flush valves for one piece toilet types mount inside the tank using a “T-flange” which fits down inside and below the drain hole to pull the valve gasket tight against the lower floor of the tank.  These toilets are generally easier to work with for that reason but can have smaller tanks and be more difficult to fit.
The flush valves for two piece toilet types use a large nut that tightens down on the outer tank bottom to fasten the valve.   Installing a two piece valve requires that the tank be fully removed and then reinstalled.  This assembly process is more work, but the tank is usually larger and easier to fit with more room for the fill and flush valves.
See our “Help Me Choose” button on our home page for pictures and a guide to determining your toilet type . . .
General Sizing
Most common standard toilets are generally considered to be either “2-inch or 3-inch” by naming convention. This refers to the INSIDE pipe diameter within the toilet and down through the floor drain. There are also some in between and larger size toilets, but these are considered non-standard and require fittings from the original manufacturer because no standard flush valves of any type will fit, whether they are standard flapper or dual flush piston valves.
Since the toilet size refers to the inside pipe diameter, this means the drain hole cut-out inside the tank will naturally be larger. How much larger depends on the initial hole cut-out and the after-cure tolerance of the ceramic or plastic composite during manufacturing.
Flush Valve Drain Hole Sizing
In most cases for 2-inch toilets, this will result in a drain hole size in the range of 2 3/8″ to 2 3/4″ and so the flange and gasket combinations on our 2″ dual-flush valves will fit and seal this size range effectively. Any drain hole size larger than 2 3/4″ does not allow enough gasket overlap and may result in leaking.  To solve this potential problem with larger drain hole sizes, we offer an optional shim washer set that fits onto the flush valve and provides the additional overlap required to cover and seal the larger tank drain, see part number WSHR2-2ST1.
Similarly for 3-inch toilets, the drain hole should fall in the range of 3 3/16″ to 3 3/4″ and so the flange and gasket combination on our 3″ dual-flush valves will fit and seal that range.  Any drain holes size larger than 3 3/4″ does not allow enough gasket overlap and may result in leaking.  But we also offer an optional shim washer set for this sizing problem as well, see part number WSHR3-2ST1.
Note that in most cases, the toilet size can be determined by measuring the lip of the flapper valve base. If the flapper lip is roughly 1 7/8″ to 2 3/8″ in diameter, that indicates a 2-inch toilet. If it is more in the 3″ range, that is most likely a 3-inch toilet. See our illustration of measuring the flapper valve base lip over on the Products > Help Me Choose tab.
In other cases where the flapper base is an odd design or the valve is not a flapper type, the valve and tank will need to be removed to allow direct measurement of the tank drain hole.
Flush Valve Height and Tank Sizing
The inside height of most standard toilet tanks as measured from the bottom of the tank to the inside top of the lid is around 12″.  When mounted, our 2″ flush valves are 8″ high, but require 10″ of height overall for proper clearance of the flush cable.   Similarly our 3″ flush valves are 9″ high, but require 11″ of height for the cable clearance.
There also needs to be enough width and depth inside the tank to allow for the other components to all mount and fit together without interference.  In most cases, this is not a problem, but in smaller tanks, it make take some trial and error in rotating or otherwise repositioning the various components to get everything inside.
For toilets with low profile or otherwise very small tanks, it is best to stick with the original factory components because it is unlikely than any of the standard retrofit kits will fit.
Filler Valve Inlet Hole Sizing
The filler valve inlet hole in the tank is much easier to fit because it is almost always 1″ or slightly larger and fits standard 15/16″ threaded filler valves. Most filler valves, including our models, will fit and seal a hole size in the range of 1″ to 1 3/8″.
Flush Handle or Push Button Actuators Mount Hole Sizing
The flush actuator mount hole can be a little tricky sometimes because there are two commons sizes, 5/8″ and 3/4″ square, which will also vary a little due to the same manufacturing tolerances. Most flush actuators, whether lever handle or push button, will have a removable rubber collar that will accommodate both sizes. All of our kits have this collar arrangement unless otherwise specified. In extreme cases where the hole is a little smaller than 5/8″, the plastic shoulder of the flush mechanism may need to be sanded or filed slightly. Then on the other extreme, where the hole is slightly larger than 3/4″, the rubber collar may need to be shimmed with tape or other suitable material to enlarge it further for a tight fit.
Still other flush actuator mount holes are round or odd-sized, again intended for a specific manufacturer actuator.
Anytime a non-standard smaller hole size is encountered, there is always the option of enlarging it with a ceramic file or grinder. This may sound like a lot of work, but in most cases, the hole only needs to be enlarged slightly and the ceramic or plastic composite usually cuts away fairly quickly and easily. Then upon completion, the resulting fitting hole is now at a standard size and can accept any number of standard fittings on the market.

Most toilets are single flush, meaning you push the flush lever down and it simply activates a full flush cycle, using the same large amount of water each time. A dual-flush conversion kit replaces the single flush mechanism in the tank, known as the “flapper valve”, to allow for two different flush cycles: the same basic “full flush” and then a water saving “half flush”.

As with any DIY plumbing project, the satisfaction level depends on the installer’s expectations, skills and tools. Most average home DIY types can install these kits without problem and realize a significant water savings. However, some installers lack the necessary skills or tools and fail to research the scope of the job prior to attempting the project.
Plus, many suppliers do not provide the level of instructions or support like we do. If you are uncertain about installing a kit or which kit to install, please study over our website and videos and feel free to ask questions.
Also note that most dual flush kits are made with industrial quality POM plastics and are priced for the home consumer market, so they are certainly not like the $500 all-metal units you may have seen in an office building bathroom.

Believe it or not, in most households, the toilets use MORE water than ANY other appliance . . . more than the shower, dishwasher or clothes washer. If you stop and think about how often a toilet is used per day, it adds up and makes sense. An average family of 4 can save over 10,000 gallons per year with dual-flush and depending on the local water rates, can easily pay for the conversion kit in a couple of months.

The dual-flush valve is a modern, double-float piston mechanism that controls the amount of water released by the position of the floats. Once installed, the float positions are adjusted for the desired amount of water for each flush cycle.

Dual flush toilets have been common in Europe and Asia for over 20 years and with water becoming a bigger issue worldwide, are now gaining significant popularity in the US as well. So dual-flush hardware is not some radical new idea, but quite the contrary, is a mature and proven technology.

Depending on the water conditions, a dual flush valve (not the flush handle – explained below) will usually last 3 – 5 years, whereas most flappers have to be replaced every year or so. However, if the water is overly harsh with high chlorine or mineral content or if the toilet is in a high use area, then the dual flush may not last any longer than a flapper. While the water savings more than makes up for the cost of a dual flush valve, it is a more complex device than a flapper and may need to be maintained or replaced periodically as with any other consumable plumbing device.
Note that the flush handle and flush handle mechanism in most all home dual flush kits, regardless of manufacturer, are made from some type of industrial plastic.  This is because metal components cost up to ten times more to manufacture and tend to corrode and gum up, causing further problems.  Further, the dual flush valve is a very light weight system that incorporates a pair of plastic trip floats inside to set the half or flush levels, so like the filler valve, the flush valve float and associated components have to be plastic to work properly.
If you have an environment where people are rough on the flush handle, it can be broken off fairly easily if slapped down hard or kicked as sometimes happens.    In that case, it is best to stick with a basic standard flapper and flush handle for maximum longevity as the more complex dual flush mechanism is naturally more delicate regardless of manufacturer.  But even the flapper style handle you will find in the hardware stores today is plastic unless specifically noted otherwise, so look at the parts carefully.

Any home handyman or DIY type who is familiar with basic toilet plumbing can install these kits using common tools. Like any plumbing project, it can get a little messy and the adjustments can take some patience to get right, but as you can see from our online feedback, most customers get them installed quickly and easily with very satisfying results.

The drop-in kit is by far the easiest to install because the toilet tank does not need to be removed. It simply slides down over top of the existing flapper body and clamps into place, which can literally be done in minutes. If the flapper body and seals are in good shape, then this is a convenient option. If not, then it’s best to remove the tank and install a regular kit from scratch.
See the video above on drop-in kit installation.

Two reasons . . . first, it’s a big and expensive job to switch out a whole toilet. New dual-flush toilets range in cost from $150 to $400 and the the labor to install one adds quite a bit more. Second, it simply doesn’t make sense to put a perfectly good toilet into the landfill when it can easily be retrofitted with a dual-flush kit and work nearly as well as a newer model.

The answer is largely personal choice . . .
The lever model is the most familiar because it looks and works much the same as a single flush toilet, but it is also easier to abuse and may not last as long if kids are rough on it.  Further, first time users may not understand the up-down or left-right dual-flush action, but we do provide flush stickers for marking the flush direction if desired.
The push button model is the most popular in Europe because of its modern appearance. It will generally last longer, but may also confuse some first-time users who haven’t seen it before.  However, the confusion factor for either model is usually not a problem if the included flush stickers are used.  Also, the push button does not have the leverage of the flush handle, so it may be a little harder to operate for children or any person lacking hand strength.

Both filler valves are similar in design with adjustable height mechanisms and bowl filler valves, plus removable internal filters.  The FillerSaver A has a slimmer design, a Snap Lock extension mechanism and a lower profile bowl filler which is better paired with smaller toilet tanks and certain kits.  The FillerSaver B is a little bulkier with a rugged Twist Lock extension and a higher profile bowl filler that is easier to adjust.  Either will work fine in most applications . . . see the Toilet Tank Filler Valves menu selection under Products for complete details.

Yes, but it’s not recommended because as a safety feature against accidental scalding, the mixer inside always blends some cold water with the hot, so if only one line is connected, there will naturally be some leaking from the other port.
If a single line installation is required, simply cap off the other port or use a “Y” fitting and connect both ports to the same line.  For a more permanent solution, fill the unused port with epoxy to seal it off.  Check your local plumbing or hardware store for different fitting options.

Chlorine tablets can be used interchangeably, but bromine is recommended because is it less harsh and produces almost no smell.  Chlorine does tend to be less expensive and is usually more readily available, but it will have that chemical / pool smell and will also reduce the life of the tank components somewhat.

Our TimeSaver Stainless Steel bolts sets not only resist corrosion for long life, but also include a complete set of nuts and washers, some of which may or may not be required depending on the toilet tank configuration and installer preference.

At a minimum, all that is really required to fasten the cone washer bolts is a single washer and nut or wingnut tightened down from below.  However, for ease of installation and assuming there is enough clearance between the tank and bowl, a washer and nut can be used to secure the cone washer bolts to the tank prior to reattaching the tank.  Then the bolts will not get knocked loose and fall out as the tank is installed back onto the bowl.   Then the wingnut can be used from below to tighten down the tank.

For general installation, remove all the bolt hardware except for the Cone Seal, then pass each bolt through the tank holes as required . . . note that some toilets use 2 bolts and other use 3 bolts.  Now use a metal or rubber washer as preferred and the regular nut to hold the bolts into place.  Tighten the nut down just enough to hold the bolts in place . . . finger tight is fine.

Once the tank is in place, fasten it on with the rubber washers (optional but provides more cushion and additional seal), metal washers and then the wingnuts. Finger tighten the wingnuts just enough to snug up the tank, usually another 1 to 2 turns additional turn they start to feel tight and the Cone Seal starts to bulged slightly.  After filling the tank, it will settle some from the weight of the water, so check the winguts again and watch for any leaking.