I’ve read these 2 topics:
Water, lava, and griefing by @Jeffrotheswell
Water, Fluid System, Farming and Weather by @Heurazio
with @james and @lucadeltodecso from developer side and with numerous ideas, each with their pros and cons. I dont know what are the current plans, but after reading the posts about it, I found some solutions, and all need to remove placeable liquid blocks from the game (those which ones the devs handing out to players).
First, my idea: ‘liquid fountain blocks’. So we can craft and place a block which will pump out liquid to the direction it faces (it can face upwards too, and then the liquid will go one block up from the ‘liquid fountain block’, then flow away in a direction). It works like the power core or like the portals, but its fuel are a liquid. If it runs out of liquid placed in it, then the flow will stop, so you need to constantly bring the desired liquid to it. Oh and of course they can be placed only inside your beacon!
We need craftable ‘liquid buckets’ for this idea, and it is a tool. You go to a natural liquid source block, use your empty ‘liquid bucket’ on it, and it will fill the bucket. The filled ‘liquid buckets’ are the actual fuel for the ‘liquid fountain block’, you place them in it, and it will empty them. Of course you cant fill your buckets with the ‘liquid fountain block’, because it doesnt create liquid source blocks, it just pours out liquid. Like when you place a liquid source block (like on Elop Portas aquaducts top), that can fill up the bucket, but what flows from that block cant. Of course in natural sources there are flowing liquids too, they cant fill up the buckets too, you need to find the source blocks! And in 1.0 (if the devs dont hand out liquid blocks like now) you can find liquid source blocks only in their natural places. From the ‘liquid fountain block’ you can get your empty ‘liquid buckets’. But as I said it is a tool, so every time you go and fill them (or die), they will lose durability like other tools!
There could be a ‘water fountain block’ made from base metal (copper or iron) and a ‘lava fountain block’ made from titanium (and other recipe components). This applies for buckets too, so ‘water bucket’ from base metal and ‘lava bucket’ from titanium. The filling mechanic would work like when you load your slingbows with damage crystals or the totem with the warp location picker upgrade.
Second, the pump system, which one were the idea of many people, but here is mine about it. It needs 3 craftable components: the ‘liquid pump’, the ‘liquid pipe’ and the ‘liquid tap’. You need to place the ‘liquid pump’ next to a natural liquid source block, the ‘liquid pipes’ would work like the ‘spark cords’, and you could place any ‘liquid tap’ next to a ‘liquid pipe’. You could place these only inside beacons too! The ‘liquid pump’ works like the ‘spark core’, you need to fuel it with the normal spark and furnace fuels (wood, compact peat, coal), and until it is fueled, and there are a natural liquid source block next to it, it will operate. The ‘liquid pipes’ connects the ‘liquid pump’ with the ‘liquid taps’. And if the ‘liquid pump’ works, and you place a ‘liquid tap’ next to a ‘liquid pipe’ connected to the pump, then after the placement from the tap the desired fluid will flow (downwards). Or we could use ‘E’ on the taps to open/close them. Again the water pump/pipe/tap could be made from base metal (copper or iron), and the lava pump/pipe/tap from titanium (and other parts of the recipe of course).
With these you will need to constanly maintain your own water/lava supply, just too much work for griefing (and if we will report the grief, the devs will anyway delete the ‘griefing station’, so the griefer must make all the things again, if he/she will be not banned anyway), but enough for normal players.
I come up with a bit crazy idea 
What if liquids weren’t liquid at all, I mean if they would not flow, they are just regular “block” filled with water, lava, lemonade 
So what you would do is just place water block where you want it and that would be it. Blocks would be obtained with liquid tool which “mines” liquids, so you find natural water, mine yourself some water blocks and place them where you want them. If you want to create larger bodies of water you would have to do quite a bit of mining.
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