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Have you ever used a toilet without washing your hands afterward? Sometimes, it skips your mind to clean them. But other times, you were just downright lazy to wash your hands. Either way, it’s gross walking around the house with dirty hands.

You can stop this bad habit with a toilet-sink combo that’ll always give you a gentle reminder to wash your hands after you flush.

In this article, we’ll take you through everything you need to know about the Best Toilet Sink Combos. We’ll also review two top sink tops that you could add to your existing toilet if you want to make it a toilet-sink combo.

How does a Toilet-Sink Combo Work?

The biggest scare people have about toilet-sink combos is that they could be washing their hands (or mouth) with water from the toilet’s tank. With how most of them are designed, we can see why many people think so. However, there’s no reason to be disgusted.

When it comes to toilets with a sink on top, the faucet in the toilet-sink combo is connected to the water supply. So, freshwater from the combo’s water supply pipes bypasses the tank and goes straight to the faucet. Therefore, the water from the faucets is as clean as what you would have gotten from your conventional bathroom sink.

Your hand washing window begins immediately after you flush the toilet. And when you are done washing, the soapy water flows from the sink through the tank to the toilet bowl in most designs.

Toilet Sink Combo Reviews


1. Sink Twice (Best for Water efficiency)

Sink Twice is a plumbing adaptation that turns regular toilets into a water-saving combination. The sink is sleekly designed to allow automated and touchless handwashing just after you finish using the toilet. As one of the exciting ways to save space, we think this product works well in small bathrooms or areas with tight layouts. It also has a one-year warranty that covers the sink, its faucets, and pipes.

There are lots of exciting features about this product, but first, let’s take a look at the product descriptions.

Product Description

  • Color: White
  • Finish: White
  • Shape: Curved
  • Product Dimensions: 8.8 x 17 x 2.2 inches
  • Product weight: 2.6 pounds
  • Installation method: Self-installation
  • Flush Type: Compatible with single flush tanks
  • Rough-In: 1 inch

Pros (What we like)

  • The sink has a soap holder, so you can keep your soap containers on the basin.
  • The drain is designed to prevent splashing while washing your hands.
  • This model’s faucet allows you to wash your hands for a long time, while still being water efficient.
  • This unit is made to work with universal valves. So, any Korky or Fluidmaster valve will work well with it.

Cons (What we don’t like)

  • The sink only works with tanks that measure between 14 to 16.8 inches when the lid is off, and there is no option to extend the unit if your tank is very wide. Although carving out the inside makes it fit smaller toilets, doing that will make the warranty on the product void.
  • The bowl might get discolored quickly. Although this is expected from any toilet that uses greywater to clean a toilet, Sink Twice’s bowl gets discolored quite easily.

Our Thoughts

There are not a lot of things to not like about the Sink Twice. It is a functional and well-designed unit. The product also scores cool points in our books because it is sturdy.

One of the best features of this unit is its patent fill cycle diverter, which solves part of the problem of using greywater to flush the toilet. The diverter allows about 40 or 60% of clean water from the refill tube to get into the overflow tube. The remaining percentage of water goes to the faucet. Alternatively, you could get a tank cleaner disk for this unit, so that you wouldn’t have to use only greywater to flush your toilet.

There’s really nothing you can do about the unit’s size, but we think it might fit most regular gravity-fed toilets that have tanks. The product also has options to increase the pressure if you use a low-pressure toilet system.

In summary, we think this product delivers on its promises. However, we might have liked it better if its drain was in the middle instead of at the right side.

2. Sink Positive (Best for Compatibility)

Sink Positive is another product that you can use in converting a regular toilet into a combo unit. The manufacturer claims that this unit can save up to two gallons of water under normal use, which will likely reduce your water bills, and they’re right. The compactly designed product also helps in identifying leaks in the toilet. Furthermore, it is pretty easy to install, and shouldn’t take you more than 10 minutes to get everything together.

Sink Positive is ideal for bathrooms that require small wash areas, and it encourages handwashing after every flush.

Product Descriptions

  • Color: White
  • Finish: White
  • Shape: Curved
  • Product Dimensions: 21.5 x 8 x 4 inches
  • Product weight: 3 pounds
  • Installation method: Self-installation
  • Flush Type: Compatible with single flush tanks
  • Rough-In: N/A

Pros (What we liked)

  • The unit works for a wide range of toilet shapes and sizes. It has an adjustable filler panel at its right side to accommodate wide tanks.
  • The product has a soap holder on its left-side, so you can keep your soap dispenser on it.
  • The hands-free faucet of the unit is high enough (about 8 inches) to prevent interference when washing your hands.
  • Sink Positive is compatible with single flush toilets.

Cons (What we don’t like)

  • The product is made from plastic, and it is not sturdy. This implies that if you accidentally drop it, it will definitely break.
  • You can only use this unit with cold water since warm water isn’t supplied to most toilets.
  • The toilet doesn’t allow for some clean water to flow into the tank. So, you’ll have to use only greywater when flushing your toilet.

Our Thoughts

The Sink Positive is one unit you should consider getting if you want to save money on water bills. This standard version has no aerator, and it has a fancy design that blends with many existing toilets. If you didn’t know any better, you would think that this unit came with your existing toilet.

Although the Sink Positive is made from molded plastic, it doesn’t scratch as easily as many people think it would. It has a finish of the same color as most toilets, which gives it it’s glossy and a porcelain look.

We don’t think the fact that this unit doesn’t work with warm water should be a red flag for you. You may need warm water for other functions, but we don’t think it’s a game-changer for toilets.

In a nutshell, using this unit is one of our favorite ways to fit a toilet and sink in a small bathroom. The toilet-sink combo might be worth your money if you don’t have a lot of space to work with.

Buying Guide


Benefits of using a toilet-sink combo

1. Toilet-sink combos efficiently use water

Toilet-sink combos encourage efficient use of water. Some models will save you as much as 70% of the amount of water you would normally use if the toilet and bathroom sink were separate from each other. For example, these toilets might allow one gallon of water for washing and flushing, instead of washing with a gallon and then using another to flush.

2. They save space

One of the most advertised features of toilets with sinks on the top is that they save lots of space in a bathroom. Therefore, they are suitable for small bathrooms.

3. Toilet-sink combos are easy to install

Never mind their unique design. These toilets are easy and quick to install. Instead of the usual hours it takes to put a conventional toilet together, installing a toilet-sink combo should take you all but 5 minutes.

4. These toilets are easy to clean

Toilets with sinks on top are one of the easiest to clean. For conventional designs of a combo, that is, the sink on top of the tank, there’s no sink bottom or tank top to clean.

How to install a toilet-sink combination unit

Here are the steps to follow when installing a combo unit in your bathroom:

1. Measure the space you have in your bathroom

If you have enough space for a toilet and a basin, then a toilet-sink combo should fit in your bathroom. But to be double sure, measure the available space and determine the layout.

2. Check your plumbing system

The plumbing system of a toilet-sink combo is similar to that of a standard toilet. However, you should check it out to know if you need to tweak anything before installing this type of toilet. Ideally, you should only have to worry about connecting the water supply pipelines to the faucet.  But you’ll need to close your existing sink’s valve if you have one.

You might need to call your plumber if you are unsure of how to get these things done.

3. Pick a combo sink

The next step is to pick a combo sink to install if you already have a toilet in place. However, you can get a complete toilet-sink combo unit if you want to replace your existing toilet.

4. Turn off the supply line and disconnect the hoses in the tank

These pipelines need to be turned off so that water doesn’t fill your tank during installation.

5. Connect the faucet and the drain hose to the sink

Use the fittings for each pipe to ensure that they stay in place. Not every sink-toilet combo has a drain hose.

6. Ensure the sink sits in firmly and turn on the water supply

When you are sure that everything is in place, then you can turn on the supply unit.

Frequently Asked Questions about Sink-Toilet Combos

Q1. Wouldn’t it be uncomfortable to use an overhead sink attached to a toilet?

The scare for many people is that their heads will hit the sink when sitting on the toilet. However, this is nothing to be worried about. You wouldn’t even notice that the tank top has been replaced with a sink until it’s time for you to flush the toilet.

Q2. Can the faucet in the sink tops of these combos be replaced?

You might be lucky to find a sink-top model that has a detachable faucet. However, most of them, come as a single piece with the basin. This shouldn’t be a problem for you as long as the faucet doesn’t disturb you while you wash your hand.

Q3. Do I need to clean the toilet tank often?

Since the water from your hands runs straight into the bowl, we recommend that you clean the tank once in a while. If you don’t want to clean it by yourself, then you can give your plumber a call to come and help you out.

Q4. Do I need to attach an aerator to the faucet?

An aerator works to reduce the water pressure when washing your hands. If you need more handwashing time, then you should consider getting one for your sink tops. Furthermore, they might also help prevent splashing when you’re washing your hands.

An aerator doesn’t greatly reduce the time it takes to fill your toilet’s tank.

Final Words

Toilet-sink combos are not new products in the market, but they aren’t as popular as other types of toilets. Although they don’t cross the minds of many buyers, these combos could be the perfect solution for a tiny bathroom that needs a sink and a toilet. But by far the most advantageous feature of these innovative units is that they are water efficient.

Picking the right size for your toilet plays a huge role in deciding whether you’ll like using these units or not. So, make sure you consider all the available options before you pick a complete toilet sink combo or a sink top for your existing toilet.