MOTAT has over 300,000 items in its collection. The Museum is organised into sections that work on various areas of the collection. Each section has a manager who works with the many dedicated volunteers in that section, and liaises with MOTAT staff to ensure the continuing development of the museum.
The old Western Springs pumphouse was in operation from 1877 until 1902. Designed by the engineer, William Errington, the building housed a large steam driven beam engine which pumped the springs water to supply Auckland. The interior has cast-iron columns, a panelled ceiling and a finely detailed staircase while the exterior is large arched doorways and round-headed windows. The building is one of the main features at MOTAT and is an important example of Victorian industrial architecture.