Here's a link to a specifically germicidal bulb for reference.
In addition to Richard's suggestion of trouble about creating something where there is about 1/64" of glass between water and voltage, there is another aspect of concern:
Most PVC isn't UV rated.
You could end up with a very brittle container which could burst or crack during use (possibly breaking the bulb and electrocuting you while you attempt to stop the geyser of water), or else one which develops pinholes and might leak for days or weeks before you noticed that your UV sterilizer had become a sieve.
PS.. The same company who I linked to has a two pin bulb that appears to be the same one that Drs Foster sells as a replacement for the Coralife Turbotwist. However, its only about $2 cheaper on the other site. In my opinion, that's not worth the possible savings to find out if its indeed the correct bulb.