Johannesburg Water outages of 48–72 hours are now a regular event across Sandton, Midrand, Fourways and Bryanston. A proper backup water system means your family doesn't notice — toilets flush, showers work, the kettle fills. Here's the right way to build one.
What "backup water" actually means
A backup water system has four parts that have to work together:
- Storage: a SABS-approved polyethylene tank (or several linked tanks) of the right size.
- Top-up: a float valve on the tank that fills automatically from the municipal main when supply is on.
- Pressure: a pump and accumulator that pressurises the house off the tank.
- Changeover: a valve that swaps the house between mains and tank automatically.
Miss any one of those and you have a tank in the garden that doesn't actually do anything when the water goes off.
How to size the tank
- Drinking + cooking + handwashing: 10L per person per day
- Toilet flushing: 30L per person per day
- Showering: 50L per person per day (short showers)
- Laundry and dishes: 40L per household per day
A family of four averaging "normal" use needs roughly 400L per day. For 3 days of outage, that's 1,200L minimum — round up to a 2,500L tank to allow for guests and a hot day. Households running a pool top-up and irrigation off the same tank should plan on 5,000L.
Pump or gravity feed?
Gravity feed (tank raised 1.5–2m on a stand) gives you about 0.2 bar of pressure — enough for a toilet cistern and a slow tap, but not a shower. For real-world household use you need a pressure pump. We use 1.1kW – 1.5kW Italian or German pumps with 24L–50L accumulators, sized to the number of bathrooms.
Automatic vs manual changeover
A manual ball-valve changeover (R850 fitted) works, but you have to physically go outside and switch it every time water goes off. An automatic changeover (R3,500 fitted) does it silently in the background. Given that most outages start at 2am, the automatic version pays for itself in convenience the first month.
What it costs, all in
- 2,500L backup with auto changeover and 1.1kW pump: R14,500 – R18,000
- 5,000L backup with auto changeover and 1.5kW pump: R22,000 – R28,000
- Plumbing COC included on both packages.
Common mistakes we have to fix
- Tank installed below the mains tap — won't fill when the mains is on.
- Pump wired off a plug instead of a dedicated breaker — fails the COC.
- No accumulator — pump cycles on every tap, burns out in 18 months.
- Pump and tank in direct sun — UV kills the pump seals and grows algae in clear tanks.
Tired of every water outage? Book a free site visit on 082 886 9119. We design and install backup water systems across Sandton, Midrand, Fourways and Bryanston.