Segment Information (Disaggregated Revenues by Reportable Segment and Geographical Region) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting [Line Items]
Net sales	$ 395.9	$ 380.3	$ 1,098.5	$ 1,048.9
Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	215.3	216.6	606.6	607.4
Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	180.6	163.7	491.9	441.5
Central \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	59.3	56.9	177.7	163.5
Central \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	51.9	40.3	145.1	115.5
Northeast \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	39.1	38.1	108.3	112.1
Northeast \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	40.1	31.0	106.0	88.3
Southeast \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	50.4	48.4	148.1	137.4
Southeast \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	40.0	38.5	115.3	99.0
West \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	48.8	57.4	129.3	152.2
West \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	29.9	35.7	77.3	93.5
United States \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	197.6	200.8	563.4	565.2
United States \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	161.9	145.5	443.7	396.3
Canada \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	15.0	13.5	35.8	34.1
Canada \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	11.4	10.9	27.4	24.5
Other international locations \| Other Operating Segment \| Water Flow Solutions
Segment Reporting [Line Items]
Net sales	2.7	2.3	7.4	8.1
Other international locations \| Other Operating Segment \| Water Management Solutions
Segment Reporting [Line Items]
Net sales	$ 7.3	$ 7.3	$ 20.8	$ 20.7