EN 71-8 vs. EN 16927: 400mm Pool Depth Explained

For pools sold in the European market, 400mm is an important water-depth threshold when considering EN 71-8 and EN 16927.

A common question is whether this depth should be measured from the manufacturer's printed filling line. The answer is no. For the relevant 400mm threshold, the standards refer to the distance between the overflow level and the deepest point within the pool.

How Is the 400mm Water Depth Measured?

Three measurements should not be confused:

Measurement	Meaning
Pool Wall Height	Physical height of the pool structure
Recommended Filling Depth	Water depth at the manufacturer's recommended filling line
Overflow Water Depth	Vertical distance from the overflow level to the deepest point within the pool

For a pool without a separate overflow outlet, the overflow level is generally where water begins to spill over the pool wall.

The 400mm threshold is based on overflow water depth, not the printed filling line.

Example: 420mm Pool Wall, 350mm Filling Line

Consider a pool with a wall height of 420mm and a recommended filling depth of 350mm.

If the pool overflows at the top edge and the interior floor is level, its overflow water depth is approximately 420mm.

Therefore, although users are instructed to fill the pool only to 350mm, the relevant depth for the 400mm threshold is approximately 420mm.

A lower printed filling line does not by itself change the pool's overflow depth.

EN 71-8 vs. EN 16927

EN 71-8:2026

EN 71-8 covers activity toys for domestic use, including paddling pools classified as toys.

For the relevant definition, the maximum water depth is 400mm, measured between the overflow level and the deepest point within the pool.

Toy pools with a water depth over 400mm are outside this scope.

EN 16927:2017

EN 16927 covers specific safety requirements and test methods for domestic mini-pools.

Its mini-pool definition includes pools with:

Water depth greater than 400mm
Maximum wall height below 850mm
Effective water volume below 6m³
No required filtration or water-treatment equipment

	EN 71-8	EN 16927
Relevant pool type	Toy paddling pool	Mini-pool
400mm threshold	Up to 400mm	Over 400mm
Depth reference	Overflow level to deepest point	Overflow level to deepest point

Water depth alone does not determine the applicable standard. Product classification, construction and other scope requirements must also be considered.

Does the Printed Filling Line Change the Classification?

Not by itself.

The filling line indicates the manufacturer's recommended water level during normal use. The 400mm threshold, however, is based on the overflow level.

Recommended filling depth and overflow water depth should therefore not be used interchangeably when evaluating EN 71-8 and EN 16927.

FAQ

Is 400mm measured from the printed water-level line?

No. It is measured between the overflow level and the deepest point within the pool.

Does every pool over 400mm fall under EN 16927?

No. The pool must also meet the other scope conditions of EN 16927. Other standards may apply depending on the product.

Does every pool below 400mm fall under EN 71-8?

No. EN 71-8 applies to relevant activity toys. Water depth alone does not determine whether a pool is classified as a toy.

Key Takeaway

For the 400mm threshold in EN 71-8 and EN 16927, look at the overflow water depth, not simply the manufacturer's recommended filling line.

For the difference between physical pool height and normal-use water depth, see our related guide:

Pool Wall Height vs. Usable Water Depth

EN 71-8 vs. EN 16927: Understanding the 400mm Pool Depth Rule