What to do with spontaneous discharge of water in the toilet?

Good afternoon. Your problem is that the drain valve button is not equipped with a snap ring, if I understand you correctly. As a result, when the lid of the tank is lifted, or when it is shifted, the entire flush stop valve also moves. Accordingly, water is washed off, and not spontaneous, as you say, but quite natural.

The lid of the tank here does not play a special role, in theory, with a retaining ring, it will not walk around the tank so much, it will fix it tightly. Or you have some special fittings, not a spring type flush, here you have not described in detail, I need more information.

Solution # 1 - complete replacement of the drain tank fittings. It costs a penny, and changing it is not so difficult with your own hands.

If you do not want to part with the old fittings, the flimsy-holding tank lid, as you say, can fall and break at any moment, at the same time damaging something else, the toilet itself, the tiles on the floor. My friend had something like this in practice. We stayed for a while with my brother in a free apartment, and the child strongly pushed the lid of the toilet bowl. The button fell out along with the fittings. As a result, the lid fell and crashed.

By the way, there are a number of stores from manufacturers where covers for flush cisterns of the right size are made, apparently, the problem is urgent with us. But such a solution is reasonable only for expensive tanks, since the cost there is from 3000 rubles. You can also place an ad - people who change the toilet will gladly sell you a cover for a penny, but it takes time. A friend just bought a new tank in the end.

Solution # 2 - you can try to just fix the lid. Doing this on adhesive tape is inconvenient, on glue - there is no access to replacing the fittings. But there are such special devices called “flexible latch on the refrigerator door” - this is an ingenious protection from children.

She has 2 either suction cups or self-adhesive buttons (option 2 is preferable).A harness lock is put on them, which prevents the refrigerator from opening. When needed, an adult can easily take it off. Cost from 100 rubles, the Chinese can be found much cheaper. Glue them on a dry, pre-greasy surface. I think with their help, the lid will be securely locked.

Here are 2 options for solving the problem. Good luck