Having wanted to do this for years but been put off by the difficulty of installing the older, barrel-shaped tanks in a restricted space where we'd have had to dig too deep, too close for comfort to this old house's non-existent foundations, I jumped at the chance to buy one of the new shallow tanks this spring.

Of course, the weather made it impossible to finish digging out the pit for most of the first few weeks after the tank arrived but I'm now almost there - just a bit of…