Many years back, when I had so many young children, I cleared out everything from under my sink and stored them all in a lockable cupboard. As the years went by, and small children became bigger and then adult and then all left home, I continued with this, (although often only locking that cupboard when g.children visited).
So, under my sink - at my house (before I moved) I kept my pyrex bowls, colanders, etc.
In the flat, thee is a large, shelved cupboard in the hall, (t think originally it would have housed the hot water tank). It is in there I keep ALL cleaning products along with vacuum cleaner, mops, broom, ironing board, etc. etc.
When I first arrived I just put everything in there, and it was nearly a year before I got round to tidying it up and putting things where I could see exactly what I had. It is rare that I need to buy any item to go in there, as during that tidying up, discovered that most of the items I use had multiple numbers as (not being able to see what was in there), I had just kept purchasing more and more.
But under my sink........all I have are the dishwasher tabs, and the items for my washing machine and a large fillable spray bottle of White Vinegar (my main 'go-to' item for cleaning), and soda crystals.
When my new kitchen get fitted, will not even those there, as I will have a fitted rubbish bin and the tank for a hot water tank.