It's a good system, but sadly it is also a fine balancing act of knowing when to start filling them.
I drain them down and clean them as best that I can each winter, but knowing when to start to allow them to refill is always a hard one. If the water is left too long, it goes stale, which okay in respect of keeping the plants alive, but not for strong growth. But if I don't start the fill soon enough, there has been years that they haven't filled up enough to sustain watering through the summer period.
The veg garden as a whole is on a tough site. It faces north with no protection for at least 25 miles, and the soil is highly acidic. It is also a woodland garden, so tall trees also take the light. The actual growing period can sadly be very short, which more often that not restricts what can be grown. I really need a glass house, and keep promising to make myself one.
Related to the veg plot, I quite like these two freebies.
The front of a luton lorry body, turned into a storage unit.
And an outdoor potting table that I made from oak and cedar that I pulled from the bonfire area of a my local sawmill.