Segment Reporting - Schedule of Financial Information by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenue	$ 128,349	$ 125,591	$ 103,904
Cost of revenue	41,270	38,235	32,670
Gross profit	87,079	87,356	71,234
Operating expenses:
General and administrative	28,864	28,341	25,174
Sales and marketing	22,164	16,277	12,160
Research and development	17,001	17,909	20,069
Total operating expenses	68,029	62,527	57,403
Income from operations	19,050	24,829	13,831
Water
Segment Reporting Information [Line Items]
Revenue	127,725	125,428	103,851
Emerging Technologies
Segment Reporting Information [Line Items]
Revenue	624	163	53
Operating Segments
Segment Reporting Information [Line Items]
Revenue	128,349	125,591	103,904
Cost of revenue	41,270	38,235	32,670
Gross profit	87,079	87,356	71,234
Operating expenses:
General and administrative	11,678	11,040	11,504
Sales and marketing	19,744	14,112	10,496
Research and development	17,001	17,909	20,069
Total operating expenses	48,423	43,061	42,069
Income from operations	38,656	44,295	29,165
Operating Segments | Water
Segment Reporting Information [Line Items]
Revenue	127,725	125,428	103,851
Cost of revenue	40,290	38,158	32,670
Gross profit	87,435	87,270	71,181
Operating expenses:
General and administrative	7,751	6,936	6,342
Sales and marketing	13,691	11,065	9,559
Research and development	4,251	4,151	2,589
Total operating expenses	25,693	22,152	18,490
Income from operations	61,742	65,118	52,691
Operating Segments | Emerging Technologies
Segment Reporting Information [Line Items]
Revenue	624	163	53
Cost of revenue	980	77	0
Gross profit	(356)	86	53
Operating expenses:
General and administrative	3,927	4,104	5,162
Sales and marketing	6,053	3,047	937
Research and development	12,750	13,758	17,480
Total operating expenses	22,730	20,909	23,579
Income from operations	(23,086)	(20,823)	(23,526)
Corporate
Operating expenses:
Total operating expenses	$ 19,606	$ 19,466	$ 15,334