After leaving the district of Neustadt, the Rehbach flows through the western part of the Upper Rhine Valley, initially in an easterly direction, later more northeast.

In the Middle Ages, the water of the Rehbach was already diverted from Speyerbach in the village of Winzingen, which today is a district of Neustadt.

In the area of Haßloch and Böhl-Iggelheim, it was split into two parallel arms for about 8 kilometres (5 mi).

Below Böhl-Iggelheim, the Steinbach flows into the Rehbach, as does the water from the Niederwiesenweiher, a 10-hectare (25-acre) re-naturalized gravel pit.

Since 1981, large parts of the Speyerbach and Rehbach between Neustadt and Speyer, that were not used for industrial purposes, form the landscape conservation area Rehbach-Speyerbach.