Killing plants with high PH water
To avoid over watering favorite garden areas, people would move the simple hose between wash / rinse cycles, 'sharing' the water around the garden during the wash.
In theory this is fine. In practice people develop a habit of always moving the hose around in the same pattern (eg. 1st water here, 1st rinse over there, and the 2nd rinse in the third spot). This is not good for your garden and will kill plants over time.
The issue is primarily the first load of water from the washer machine. Virtually all effective washing powders, 'eco-friendly' or not, need high PH water to wash the dirt from the clothes. The PH of this first amount of water is 10.5. As the washer processes each cycle, the PH of the water in drops.
If you were to temporarily store all of the water from one wash, the overall PH is generally between 9.0 and 9.5 which is ok for most gardens.
Always watering in one area with PH 10.5 water will kill plants. If you are going to move a hose around, move in a different pattern each day.
Waste Pipe Diverters / Hoses
These diverters come in many shapes and styles. They divert water from showers (pipe under the house) and laundry (often a vertical pipe on the outside wall). Gravity hoses can then be connected to the diverter valve.
Although shower water is basically PH neutral, and therefore removes PH risk, over watering becomes a significant issue, especially when diverting all shower water, and not moving the hose each day.
Over watering remains a significant risk for laundry pipe diverter and hose sets.
Further information about Irrigation Methods
Irrigating every day
Laundry to landscape
Pumped hose / nozzle