Eight children taken to hospital after being exposed to chlorine at a council-owned pool in New Plymouth have been allowed home.
The incident happened at the Todd Energy Aquatic Centre just after 5pm on Tuesday when too much of the chemical went into a spa pool.
The children, all under 12 years old, complained of coughing and feeling unwell.
The New Plymouth District Council said it is working to pinpoint what went wrong.
Staff found a faulty valve during routine maintenance, but are unsure why extra chlorine was sent into the pool when the system was switched back on.