The Mushroom Valve is specifically designed to prevent water flowing out of the reservoir whilst filling. Should a replacement Mushroom Valve be required, please follow the steps below – This will help prevent possible damage to the water inlet valve: - Remove the reservoir from the Propulse G5 - Remove the old Mushroom Valve from the reservoir and discard - Insert a new Mushroom Valve into the reservoir - Return the reservoir to the machine - Suitable for the 2017 unit