With simple hoses, all the water (often 40 gallons per wash) is dumped in one small area of the garden, resulting in over watering that area, with other areas going dry. Similar to bucket watering, people would concentrate water in their favorite areas, in the end killing with over watering.
The most prominent symptom of iron chlorosis is leaf yellowing. The veins of the leaves stay green, while the rest of the leaves turn yellow.
If you were to temporarily store all of the water from one wash, the overall pH is generally between 8.5 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. A more sophisticated diversion system is the Branched Drain Network.