Yes, Telekinesis can manipulate liquids
The spell enables you to manipulate objects, and liquids are objects. So it enables you to manipulate liquids.
But how does it work?
You can try to move an object that weighs up to 1000 pounds
The reason it's easy to envision manipulating solids with Telekinesis is because it's one solid thing that intuitively moves together. But there is a limit of one object you may manipulate at a time. You can't move around two or three swords, even if all of them weighed less than 1000 lbs. But as soon as someone welds all three together by the handle, then it becomes one object you can manipulate. Weird, right?
But consider that there is no intuitive way to say the same for liquids. You can manipulate a sword, but can you manipulate a water? Does it even make sense to ask that question? There is no way to think of liquid-manipulation in the same way you imagine solid-manipulation.
If you consider liquid manipulation by units, you start setting arbitrary limits of power to the spell. While one longsword weighs 3 lbs and is considered one object, "one water" cannot be quantified. You instead say "one gallon of water" or "one pound of water", which is categorizing the spell into units of volume or weight -- which doesn't apply for solids. You can't manipulate "three pounds of longsword" but simply "one longsword," which just so happens to weigh 3 lbs.
So saying that Telekinesis allows you to manipulate one sphere of water weighing 1000 lbs is problematic because you can't define "one water" -- much less "one sphere of water" -- as an object in the same way you can define "one longsword." The boundaries on mass per object is not present in liquids the way it is for solids.
It depends on the DM how much they will let you get away with, but there are pitfalls
If you had a half-full cask of ale and chose to manipulate the ale itself (not the cask), it depends on the DM if they will let you do that. This is tenuous because you could take the ale from that cask via TK, put it in another half-full cask (so now you have a full cask), and now you have twice as much ale under your control as when you started. Meanwhile, you can't take a broken sword, unite it with its broken half, and have a full sword. In both cases, the idea is the same: take two halves of a whole and unite them. But for the solid case, you can distinguish the two halves of a broken sword as two objects, while you can't distinguish one full cask of ale as two distinct half-casks of ale.
If you then say, "but we can just have the original half-cask of ale under the TK spell, and that distinguishes it from the other half-cask of ale," that still has a few problems:
This is the same as claiming that whatever liquid TK controls initially becomes a distinct object by virtue of being controlled by TK -- but the prerequisite of TK is that you are already controlling one object. In other words, this creates circular logic: you are making the object you control into an object by the fact you are controlling it (that is hard to read -- but circular logic is hard to read because it is nonsensical).
You can just stop exerting control on the original half-cask of ale volume after transferring it, and then exert control of the full cask volume on the next turn. Meanwhile, you can't take a broken half of a sword, unite it with the other half, and exert full control of the entire sword on your next turn.
You can only exert fine control over simple objects. However, it can be argued that any volume of liquid is a complex object already. Take a door: you can close it by pushing the far side of it, without having to control each and every molecule of that door. Take a vial: you can pour its contents by controlling the bottom and turning it over, again without needing to control each molecule of that vial. The manipulation in both cases is simple, but the same cannot be said about manipulating a volume of water. There is no force holding them together, so you would have to manipulate each molecule independently -- which is not simple manipulation of an object and is out of the scope of TK.
If you say you are containing the water inside a telekinetic shell instead to give it shape, then you run into problems of permeability. As soon as the liquid makes contact with other creatures, it cannot absorb them or else the shell will break, causing the liquid to spill out. Also, you can't actually form telekinetic shells with this spell. Otherwise, you would be able to form a shell in a vacuum and use that to hit creatures, or form telekinetic cages like Wall of Force.
This point is a bit more involved and probably unnecessarily nitpicky. That's why I put it after points 1 and 2.
If you plan to do this in your game, just ask the DM and go with their ruling
To avoid the complex overthinking that this question invites to your table, just ask the DM how much you can get away with this usage. You can do it -- that much is clear. It's just not clear to what extent you can do it.