Buy from Alan Wright the Inventor on this site

Instant Hot Water at Taps and Energy Storage Replacing Power Showers

A 210 litre hot water cylinder will store 5.6 kW/Hrs of storage at 65 degrees centigrade. A power shower destroys the thermocline. Because ShowerPowerBoosters do not destroy the thermocline you get up to 10 perfect showers instead of 3 showers using a power shower pump if you start was a fully heated 210 litre hot water cylinder.

Power Showers use 60 litres of water per shower compared with 30 litres of water for a system fitted with a SP22S. A total of 40 litres of hot water saved per shower with instant hot water at taps and showers as well.

These are products you need to buy.

Buy a SP22S using this link to replace a power shower and save 30 litres of water per shower
Buy a WrightChoice Instant Hot Water Recirculation Pump using this link to save an additional 10 litres of water per shower
Buy a WrightChoice Engergy Storage Device

With a energy storage device fitted outside and existing hot water cylinder the whole tank is heated and you store 10 KwHr of energy.
With a energy storage device fitted outside and existing hot water cylinder the whole tank is heated and you store 6 Kw/Hr of energy.