Canada has thousands of indoor swimming pools. Unfortunately, many of them are more problematic than facility operators would like to admit. Too often, the pool’s dehumidifier is blamed and the real cause of a natatorium problem is never discovered nor addressed. Chlorine odours, mould, condensation, or poor indoor air comfort, generally have causes unrelated to the dehumidifier. Instead, they may be due to building pressurization imbalances, improper vapour barrier, poor ventilation design, unbalanced water chemistry, or unsuitable architectural materials. They can also be related to inadequate maintenance, or perhaps just a slow, unnoticed degradation of operating parameters. Additionally, a few seemingly minor items missed during design and construction can also contribute to facility problems. Natatoriums have many unique design challenges and considerations that are not always obvious to anyone unsure about these facilities’ state-of-the-art requirements.