Yes.

— Jeremy Crawford (@JeremyECrawford) January 16, 2018

@JeremyECrawford Can you l, using the wall of water spell, make a column of water, by making a tall wall of water packed tightly, and deal a bunch of damage to fire elementals using the volume of water against them? Or is that simply a dm discretion thing?

— Mike McDonell (@Stickman404) February 27, 2018

The wall of water spell doesn't deal any damage. If you want to deal damage with it, your DM decides if that use is possible. It's always in the DM's purview if you want to do something with a spell that isn't in the spell's description. #DnD https://t.co/ZrJRfVamCK

— Jeremy Crawford (@JeremyECrawford) February 27, 2018

This shenaniganry comes from the Water Vulnerability trait. People love to say things like the shape water cantrip instakills a fire elemental because of how many gallons of water are in a 5' cube.

Sometimes I hate the internet. 😛

— Dan Dillon (@Dan_Dillon_1) February 27, 2018

The Water Susceptibility trait of a fire elemental makes water dangerous to the elemental. The trait doesn't change how spells work, however; if a spell creates water in a certain number of 5' cubes, you can't compress cubes into each other to produce extra gallons of water. #DnD https://t.co/OsPmKRdPE4

— Jeremy Crawford (@JeremyECrawford) February 27, 2018

Yep, but a 5-foot cube of water is 125 cubic feet. 1 cubic foot of water = 7.48 gallons, x125 = 935 gallons in a 5 ft. cube, which people equate to "splashing" 935 gallons of water on the elemental for 935 cold damage.

(fixed brainfart math error)

— Dan Dillon (@Dan_Dillon_1) February 27, 2018

The shape water cantrip doesn’t produce water. It moves water up to 5 feet. Want to use it against a fire elemental? The smart elemental is nowhere near the body of water. #DnD https://t.co/tMeB8TSWfx

— Jeremy Crawford (@JeremyECrawford) February 27, 2018