Before revision: The preferred method of firewater containment is to use pneumatic bladders/drain stoppers that block the outflow from the drain or pneumatic non-return valves, both of which can convert the drains into containment vessels (called sumps) from which the firewater can be pumped away into tankers for safe disposal or stored temporaritily in mobile firewater tanks .
After revision: The preferred method of firewater containment is to use pneumatic bladders/drain stoppers that block the outflow from the drain or pneumatic non-return valves, both of which can convert the drains into containment vessels (called sumps) from which the firewater can be pumped away into tankers for safe disposal .