We never know the value of water till the well is dry

Similar English and Irish sayings:

You never miss the water till the well runs dry You never miss the water till the well runs dry
He that eats till he is sick, must fast till he is well He that eats till he is sick, must fast till he is well
He knows the water well who has waded through it He knows the water well who has waded through it

Proverbs and English sayings