Most EU member countries have adopted the ISO standards. However they do not address a multitude of construction, design and safety issues that are covered in the United States building codes.
International Building Code
The IBC is THE adopted building code across the Unites States (except Wisconsin). The IBC has incorporated the ACI, ASA, NEC and ANSI/NSPI/APSP standards as well as other construction workmanship related standards.
Therefore, the IBC should be a basis for defining the standards on an international project, where ISO or local codes do not address a particular issue.
International Swimming Pool Code
APSP has released an International Swimming Pool Code. While not all encompassing, it is also a good BASIC starting point. It is generic in many of the areas it addresses, because it refuses to establish a minimum level of acceptable workmanship. Where it does establish a criteria, this should be only be a "not to exceed" standard.
A copy of the 2012 International Swimming Pool & Spa Code is available at:
2012 International Swimming Pool & Spa Code
Paolo Benedetti - Aquatic Artist
"Creating water as art."™
Aquatic Technology Pool and Spa