Ten Firefighters and paramedics descended on Swim! Oldbury, at Birchley Island Retail Park off Wolverhampton Road in Oldbury, at 8.55am on Saturday.
Fire crews from Haden Cross and Oldbury were sent to the scene alongside the hazardous materials response team after reports of a "chemical incident".
A spokesman for Swim! said: "We’d like to thank the fire service and paramedics for their attendance this morning after the unfortunate accidental mixing of a small amount of incompatible chemicals in our plant room.
"We can assure all of our customers that no one was hurt as a result of this minor incident and that our venue remains safe to use."
West Midlands Fire Service confirmed around 10 people were evacuated. Two people have been treated by paramedics for breathing difficulties with this incident contained to the building.
Their full statement released early on Saturday afternoon read: "Shortly before 9am on Saturday 1 April we were mobilised to an incident at Swim on Birchley Island Retail Park, Oldbury.
"The incident involved a chemical leak within the plant room of the swimming pool. Ten people were evacuated, with two people complaining of breathing difficulties. The leak was contained to the building and posed no risk to the public.
"Two fire engines and our hazardous materials team responded, together with colleagues from the ambulance service.
"The first crew were at the scene within three minutes of being mobilised," the statement continued.
"Our teams are ventilating the building and our specialist officers are using air monitoring equipment to make sure the area is safe".