The Federation Internationale de Natation (FINA), the world sporting authority on swimming and diving, uses the following equation (taken from table FR5.3 in Annexe 1.2 of its Facilities Regulations) for the minimum safe depth of water $D$ for High Diving from a height of $H$ metres above the surface :
$$D = 0.143H+3.04$$
This can be taken as an indication of the maximum depth achievable from jumping into water from a given height. The data (column 1 : Platform Height, colmn 2 : Minimum Safe Depth) is
1 ... 3.2
3 ... 3.5
5 ... 3.7
7.5 ... 4.1
10 ... 4.5
The above formula is based on recommendations for dives of up to 10m. However, Annexe 4.2 recommends a safe water depth of 6m for all dives between 5 and 27m.
So I would guess that 7m is a fair estimate of the maximum depth you could reach from any height, unless you were carrying additional weight. This is confirmed by Laso Schaller's World Record Jump from 58.8m in August 2015. Remarkably, he plunged only about 4m under the surface.
You should also consider the likelihood of survival. Jumping into water states that a jump of more than 76m is highly likely to be fatal, and that a jump of more than 46m is highly likely to result in spinal injury - unless, like Laso Schaller, you have years of practice.