The following is a tutorial on Adobe Photoshop. It is the basis for creating water. You can always add to this to create more effects such as water in a glass etc...
Start a new document as shown below. (File -> New from the menu)
Click on the Foreground colour picker.
Select a lighter colour blue such as #7ec9fc for the foreground colour.
Click on the background colour picker.
Select a darker colour blue such as #052141 for the background colour.
Click on Add New Adjustment Layer icon (at the bottom of the layers panel) as shown below
From the popup menu select Gradient.
Now click on the Gradient Fill dropdown button
Choose the first option which is the current foreground/background colour choices.
Set Style as Linear, Angle at 90, and ensure Reverse checkbox is ticked.
Click the OK button to accept these choices.
While the Gradient Fill layer is active in the Layers Panel, right-click the layer and from the popup menu, select Convert to Smart Objects.
Now from the Menu -> Filter -> Render -> Clouds.
This produces a clouds effect with the chosen colours as shown below.
Now from the Menu -> Filter -> Artistic -> Plastic Wrap.
Note that there is now accoumulated smart filters applied to the Gradient Fill layer in the layers panel.
For the plastic wrap filter, choose Highlight Strength as 15, Detail as 9 and Smoothness as 7.
Click on the OK button to accept these settings.
Select the Smart Filter.
With the Marquee tool select the top half or top section of the image.
From the Menu -> Edit -> Fill -> Black. Note: Make sure you deselect the selection area (Ctrl+D).
Create a new layer by selecting the Add New layer button at the bottom of the layers panel.
With this layer selected, choose the smudge tool as shown below.
Use the following settings for the smudge tool. Brush size set to around 40, Mode Normal, Strength approx. 70%, and ensure the Sample All Layers option is ticked.
The end result is shown below.
It looks like the side view of water in a glass or fish tank etc...