# How to treat specific water molecules as ligand? **URL:** \ **Category:** User discussions\ **Created:** [January 12, 2022, 9:53pm UTC](https://gromacs.bioexcel.eu/t/how-to-treat-specific-water-molecules-as-ligand/3470 "2022-01-12T21:53:20Z")\ **Posts on this page:** 1\ **Showing post:** 9
**Author:** ![lanselibai](https://avatars.discourse-cdn.com/v4/letter/l/e9c0ed/32.png) [@lanselibai](https://gromacs.bioexcel.eu/u/lanselibai)\ **Post date:** [January 14, 2022, 12:54pm UTC](https://gromacs.bioexcel.eu/t/how-to-treat-specific-water-molecules-as-ligand/3470/9 "2022-01-14T12:54:05Z")
Thank you Justin, would it be possible if you can show me an example for the “three constraints” for “position restraint”? Is it the same for “position restraint” and “flat-bottom restraint” [(earlier thread)](https://gromacs.bioexcel.eu/t/solvent-partition/1034)? [constraints] ; ai aj funct length\_A length\_B 1 2 1 0.09572 1 3 1 0.09572 2 3 1 0.15139 --- _[View the full topic](https://gromacs.bioexcel.eu/t/how-to-treat-specific-water-molecules-as-ligand/3470)._