The phrase "milk and water" is often used to describe something that is weak or insipid. When looking for synonyms for this phrase, words like bland, boring, uninspiring and uninteresting come to mind. Other synonyms include vapid, insipid, lackluster, flat, and anemic. Infusions like chamomile tea, weak broth, diluted juice, or insipid wine can all be described as milk and water. On a positive note, "whole milk" can be a good substitute for "milk and water" to connote something that is wholesome, substantial and genuine. Overall, there are many synonyms for "milk and water" that connote lackluster traits, but looking for the right word to describe a precise instance, it's important to take context into consideration in order to convey exactly what's meant.