I know, it was long, I have a habit of talking too much. . . . what can I say, I like to share what I know! But you are very welcome. The milk in the Medela pump doesn't actually run THROUGH the pump, but if you let the bottle get too full, it will fill up the tubing and run behind the diaphragm (which is replaceable, as well). I agree with the other posters, though, if WIC is out for you and he REALLY won't give in, go for one of the less expensive pumps. A double pump is SO worth the investment, no matter what you pay. It's just time and effort wise, way more value!!