More on watering

Last year I bought a rain barrel but I did not get to use it much. This year, the 40 gallon barrel will be the center piece of my watering plans. The problem is that 40 gallons do not last very long, especially if I waste water, so I have to be very conscientious when watering this year. To help, I am growing most of my vegetables in self-watering containers. Some of my vegetables are growing in 5 gallon buckets with watering spikes in them, and a few, will be growing on the ground.
For the plants in the ground (mostly peas and beans) I have designed this simple drip watering scheme:

To achieve the drip, I think I can stuff some left over garden cloth in the holes of the pvc pipe.

For the plants that have watering spikes (I have both plastic and terracotta spikes) I am thinking of something like this:

The idea here is to use as little city water as possible. I also have a well but I am still working on how to integrate it into my watering plan. The well is connected to the sprinkler system that broke last year. To use it, I will have to uncap it and install some type of pump.

One issue that has been discussed at length in gardening forums is the use of PVC pipe when watering eatable plants. It's been said that PVC pipe, when heated and exposed to conditions common in a garden, leaches harmful chemicals into the water that the plants absorb, thus passing the bad stuff on to you when you eat the fruit of your labors. In particular, the use of PVC pipes in home-made self-watering containers is not recommended.
Me, thinking myself clever beyond reproach, decided to use aluminum tubing instead of PVC, only to find out that Aluminum ions are poisonous to plants. I did some research into the use of Aluminum piping and found out that generally speaking, aluminum is not reactive until the pH (potential Hydrogen) of the water/soil, reaches acidic levels (somewhere around pH 5) which could conceivably happen in a container plant.
The perfect material would be bamboo but I have not located a source of cheap bamboo for this purpose, so I am now using pieces of an old watering hose.
In the diagrams above, one could use watering hose instead of pipe. One could also use a watering hose INSIDE pvc pipes to gain rigidity.
A soaker hose would not work because I believe I could not get enough water pressure from the rain barrel, and if I did get enough pressure, it would soon diminish when the water level in the barrel dropped.
I will see if I have enough time to build one of these this season.