A 3-way water diverter gives a pipe run three possible destinations instead of one, with a lever or cap to choose between them. Blue Mountain Co's range covers three sizes, used for exactly the kind of job the name suggests: sending shower, basin, laundry or downpipe water onto the garden instead of down the drain, or splitting a downpipe's flow between a tank and the stormwater system.
The three sizes
The 3-Way Water Diverter 50mm ($21.94) suits smaller fixture waste lines — a shower, hand basin or laundry trough line, where the flow is modest enough for 50mm pipe. The 90mm ($36.25) and 100mm ($49.90) versions suit downpipes, matching the two most common downpipe sizes.
What they're actually used for
On a fixture waste line, a 3-way diverter lets greywater from a shower, basin or laundry be redirected onto the garden instead of always going to sewer — useful seasonally, or wherever greywater reuse on the garden is permitted locally (check with your water authority, as greywater reuse rules vary by state and by whether the water has had any treatment). On a downpipe, the same fitting lets roof water be split between a rainwater tank and the stormwater system — handy once a tank is full, or if only part of a roof's catchment is plumbed to the tank.
Installation notes
Match the diverter size to the pipe it's going into rather than rounding up or down — a 90mm diverter won't seat properly in a 100mm downpipe. For greywater reuse specifically, check local health department guidance before diverting shower or laundry water onto edible gardens; the diverter itself doesn't treat the water, it only redirects it.
See the full range in our Downpipe Diverters & Outlets collection, part of the wider Blue Mountain Co rainwater harvesting range.
Frequently Asked Questions
Can I use a 3-way diverter to send greywater onto my garden?
Yes, that's one of its main uses on fixture waste lines, but check your local water authority or health department's greywater reuse rules first — they vary by state and by what the water is being used for.
Which size do I need for my downpipe?
Match it to the downpipe: 90mm diverters suit 90mm downpipes, 100mm diverters suit 100mm downpipes. The 50mm size is for smaller fixture waste lines, not downpipes.
Does the diverter filter or treat the water?
No, it only redirects flow between destinations. For filtering roof water before it reaches a tank, see our guide to downpipe diverters.
Can I split a downpipe between my tank and stormwater permanently?
Yes — once the tank is full, or if you only want part of the roof plumbed to the tank, the diverter can be left set to stormwater, or switched back and forth as needed.