adjective
pristine
PRIS-teen/ˈprɪstiːn/
In a perfectly clean or unspoiled condition.
The pristine snow around the sapling has no tracks or debris.

Etymology
Latin pristinus meant “original” or “early,” rather than “clean.” Expressions such as “pristine wilderness” helped shift the meaning from an original condition to one untouched or unspoiled.
In context
if you keep them in fresh water you really need to keep that water pristine and clean
More examples
- Despite its age, the book is in pristine condition.
- She keeps the kitchen pristine, wiping every surface after cooking.
- The park protects a stretch of pristine wilderness.
Forms
pristine
Similar words
- immaculate
- Emphasizes perfect cleanliness or neatness rather than an untouched state.
- unspoiled
- Emphasizes freedom from damage or development rather than perfect cleanliness.