The same url for getting a WaterWatch map can also be used to customize a WaterWatch map. To do so, just add additional url variables such as 'w', 't', 'bg' for width, background transparent, and background color, respectivley.
A tool to customize a WaterWatch is available. In the tool, choose your option, and copy and apply an url in the 'URL' box to your page.
Notes:
If a standand map is required, don't specify a width in an 'image' url.