blandThe soup is very bland, it could use more herbs and spices.
tastelessThe boiled chicken is practically tasteless.
flavourlessUKThese tomatoes from the grocer's are flavourless.
insipiddisapprovingHe was drinking an insipid light beer.
watered-downThe bar served bad food and watered-down cocktails.
like dishwaterinformaldisapprovingThis tea tastes like dishwater!
weakThe punch was quite weak.