I assume you mean which gives least lather with solid soap. It will be the hardest water, that is the one with the most calcium and/or magnesium compounds.
hard water
Lather would be the combination of two, middle ground or in bathing it is the soapy, bubble mixture of shampoo and water.
Hard water does not produce lather. So soap does not work effectively with hard water as soap does not form a good lather with hard water.
lather
Supple
Water is a universal solvent and is of two types soft and hard water. Water that produces more lather when soap is added is Soft Water.
Water is a universal solvent and there are two types of water i.e hard water and soft water. Soft water is the water that easily lather with soap while hard water does not lather with soap and is also of two type i.e temporary and permanent.
A sample of water is said to be hard when it does not form lather readily with soap.
soft water easily lather witth soap but hard water do not.
Sodium palmitate produce a permanent lather with hard water..
soft water:1. makes lather with soap faster.2. use a lot of water.hard water:1. makes lather with soap in very less amount.2. soap is wasted.3. chlorides, sulphates and bicarbonates of Ca and Mg are responsible.
The purpose of having a shaving bowl is to lather up the soap really good to be able to have a nice shave. You can run hot water in the sink and then put your shaving bowl in the water to keep the lather warm during your shave.