The robbery happened in broad daylight in the 9700 block of Morefield Road.
Police say the man forced his way in and then forced the woman into a bathroom.
He then stuffed a pillow case with $2,500 worth of jewelry and ran off.
Investigators say the victim is okay.
Meanwhile, the Philadelphia Water Department is telling everyone that their employees carry ID cards, wear uniforms, ride around in marked vehicles and rarely show up unexpectedly.
"Unless there is an emergency like a water main break or a sewer failure, we typically do not show up unannounced," said John DiGiulio of the PWD. "If you're concerned, go back into your house and call us."
The number for the PWD is 215-685-6300.