Please note, this method has only been used on a flowering garden. If I was growing herbs or vegetables, I would not use this method. If you are growing food, you still may find some benefit in using the sunken pots that are mentioned later.
This method uses recycled roof guttering to act as an irrigation channel in your garden. Your garden will thrive without wasting precious drinking water. All the water is delivered to the root zone which means it is going straight to where it is needed. Water restrictions are becoming more common, so with a little bit of work now, you can still have a healthy garden and feel good about doing your bit for the planet.
I have had this system in place for 4 1/2 years. The soil is a little bit clayey. I was never dedicated to watering and my plants wouldn't thrive and would be lucky to even survive. With this system, the plants get a lot of water with no effort. I thought it would be too much water, but everything is fine so far. No effort has been made to use special shampoos. Just the regular stuff. And the fact that shower water is hot has had no effect.
If your house is on a concrete slab then this instructable is not suitable for you. You may still be able to make your current system of watering more efficient by using the sunken pots.
Step 1: Materials
PVC pipe and fittings compatible with the pipes carrying the waste water from your shower. This is likely to be 50mm-2 inch wide pipe.
Small soft drink bottle. (Optional)
19mm-3/4 inch garden irrigation poly pipe. (Optional)
Length of old roof guttering the same length as your garden and similar length of gutter guard.
Old plant pots approximately 18cm-7 inches wide at the top.
Drill, drill bit about 8mm-5/16 inch.
Step 2: Plumbing
Boring, but important to read if you are actually going to make this system.
It is important to use a good length of PVC pipe before you start using the cheap poly pipe. It would be bad if the water from your shower was suddenly squeezed into a very small 19mm-3/4 inch pipe. I didn't try it but there would be a good chance of the water not been able to flow away fast enough and been forced to rise up back into your shower. My PVC pipe runs about 12 meters under the house before it gets to the back yard and joins up with the small pipe. If your bathroom is at the end of the house near your garden, then I'm afraid I can't give you any exact guidelines on how long the PVC pipe needs to be.
Step 3: Linking big pipe to little pipe
Cut the bottom off a small soft drink bottle so that the bottle fits snugly over the PVC pipe. Put one end of some flexible type garden irrigation 19mm-3/4 inch poly pipe into the neck of the soft drink bottle.
I found a small Coca cola bottle to be perfect. Other brands didn't fit snugly. Things could be different where you are so you may need to experiment. Once you find a brand and size that fits, collect a few in case you need to replace it. Reasons to replace: accident when mowing lawn, curious dog, degradation due to sunlight.
I made this system in late 2004 so unfortunately don't remember the size of the bottle.
Step 4: Getting water to the garden
After a few days or weeks,when you are happy with the position of the poly pipe you may decide to bury it. Just take a spade and make a continuous slit in the grass, levering the spade backwards and forwards before moving along. Once you have made the slit across the lawn, just scoop out a little bit of soil with your fingers all along. Then insert your poly pipe in and stomp on the grass.
Step 5: Sunken Pots
Step 6: Water channel
Step 7: Water Spurt points
Step 8: Finishing touches
Put gutter guard in the gutter. This will keep leaves out and make it easier, but not any nicer for you to pick off any hair balls that accumulate on the gutter guard at the water outflow point.
Step 9: Check everything
Then enjoy. It's really fun to go out into the garden while someone's having a shower and watch all that water being put to good use. Sounds like a babbling brook too. Very peaceful.