I highly recommend 1 trench unless your local area requires otherwise. I'd place the water at the depth required by local code, this has to do with the frost line.. in the area... Then I'd place the electrical about 1 foot above that, then above that conduit for low voltage (alarm, ethernet, TV, etc.) Then 6-12" from the ground place a caution tape. That way if you are digging with equipment hopefully you find the tape first. IF you miss the tape you'll first hit the low voltage conduit, then the higher voltage power, and lastly the water line. Basically with them all vertical in the same trench, you only have to locate 1 of them, and if you've found one, you've found them all and you won't have to worry about digging into another one several feet away.
Burying everything in the same trench with some spacing might get more tricky if your frost line is 2" because you live in an area that doesn't freeze... If your water line is only buried 24" down, it makes it difficult to stack everything vertically... The electrical must be 24" deep or 18" deep if in conduit. The electrical and water won't interfere, but placing the electrical and low voltage too close could in theory cause interference with the low voltage... In my 200' run to my shop I put everything in the same trench. Water at 3-4' then electrical in conduit about 1' above that. I put the low voltage conduit about 6-10" away but alongside the power conduit. I didn't get time to place a caution tape before the contractors filled in the trench
Brian