Understanding Toilet Footprints: 380mm vs 305mm for 400mm Toilets

When installing a toilet, it is essential to determine the distance to the drain (pit distance) in advance to ensure a smooth installation. So, for a pit distance of 380mm, should you install a 400mm toilet or a 305mm one?

Should you install a 400mm toilet or a 305mm one for a 380mm pit distance？

Generally, it is advisable to choose a toilet with a 305mm pit distance. Installing a 400mm toilet would be quite challenging; even if you manage to adjust the position of the seal ring to complete the installation, there is still a high risk of experiencing water leakage afterward.

How to choose a toilet for a 380mm pit distance？

1、Look for toilets with specific pit distances.

Common pit distances for toilets in the market are 300mm and 400mm. There are some special types available, like 185mm, 220mm, 350mm, etc., but these are not very common. Therefore, if you have specific needs, you may need to spend additional time searching for suitable options.

2、Modify the wall.

If your home has a pit distance of 380mm, but you can’t find a corresponding toilet model and have only found a 400mm one, you may need to create a recess in the wall to allow the cistern to fit inside it, thus shortening the distance. If the pit distance is too large, you could build a wall behind the cistern or place a bathroom cabinet behind it to effectively reduce the distance.

3、Use a displacement device.

A displacement device can also help improve the pit distance situation by allowing for small adjustments, available in specifications such as 50mm, 100mm, and 150mm. However, this may affect the flushing performance of the toilet, so it is not recommended unless absolutely necessary.

4、Convert to a wall-mounted toilet.

If modifications are not an option, you can consider changing the toilet to a wall-mounted model based on the drainage direction, but not all floor plans can accommodate this. It is subject to various limitations, so it is essential to conduct a thorough assessment before installation. Additionally, this may involve significant costs.

In summary：as discussed in the article, when dealing with a pit distance of 380mm, it is best to choose a toilet with a 305mm pit distance. This ensures smooth installation and normal operation of the toilet, thus reducing the likelihood of future issues and saving considerable time and resources. I hope this information is helpful to everyone.