Thanks for the pictures. What is your garden plan? What are you growing this year? How much light does that area get near the tank? How much rain do you get each year?
It seems you do a lot in a small space.
I’m still working on the garden plan, but I do have a lot planned for this space. I’m digging the beds out about 2 feet deep and refilling them with compost and coconut coir to hold the water in the soil. Check in our weekly gardening thread for more details on what’s going in there...
That end of the house gets a lot of sun, and here in the Pacific Northwest we get enough rain year round that I do not think the tank will ever go dry.
Do you need to treat the water in any way to keep it drinkable for humans? Or does the closed system keep it in good condition?