They have descriptions and everything else, but I'm almost positive you will find what your looking for.
The Epson I have is the BX600FW and the watermark option appears under print preferences/page layout.
It may be more than you actually need though because it's a scanner & fax machine as well.
I'd imagine that a lot of the Epson printers have the facility - there's a page HERE for a different Epson model which shows how it's done. Invisible watermark that you hold up to a light to reveal itself and a Photoshop watermark with a regular printer are different. A watermark from Photoshop is simply changing the opacity of the image to make it seem diluted like adding water to an image. Having an image appear when being help to a light source is completely different and CANNOT be achieved with a simple Epson MFP.
Be sure the Background Contents is set to Transparent. PS Elements Users: Your type and style choices are across the top of your screen. This example is just the business name, but it could easily be© Andy Williams - Andy Williams - Reproduction Prohibited To edit your text layer, use the type tool (be sure it’s active by clicking on it in your tools palette).
Take your cursor, which is now the type tool, and click in your canvas on the left-hand side. Click the beginning or end of your text, and drag left or right to highlight the area.
Recently, I sent a draft article to a friend for review.
Although I expected to get a call to discuss the article, I didn’t think we would discuss how I made the Microsoft Office document.
Specifically, he wanted to know how I added the “ghost text” or Microsoft Word watermark that read Draft.
And with a little more effort, it’s just as easy to create a custom text or picture watermark. Like many people, if I send a business document which is confidential or a draft, I include a watermark.