Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Mar. 29, 2015	Dec. 28, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014		Dec. 29, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 29, 2015	Mar. 30, 2014		Mar. 31, 2013
Summary of Segment Information
Sales	$ 93,281	$ 83,825	$ 88,881	$ 98,036	$ 85,223		$ 81,697	$ 86,599	$ 94,744	$ 364,023	$ 348,263		$ 350,387
Gross profit	15,531	13,642	18,122	18,496	14,249		13,550	16,570	17,231	65,791	61,600		56,936
Selling, general, and administrative expenses	9,532	8,697	8,271	8,875	8,080		8,167	8,293	8,970	35,375	33,510		31,606
Operating income	5,999	4,945	9,851	9,621	6,169		5,383	8,277	8,261	30,416	28,090		25,330
Identifiable assets	194,017				170,507	[1]				194,017	170,507	[1]	169,275	[1]
Unallocated Amount to Segment [Member]
Summary of Segment Information
Identifiable assets	53,700				66,700					53,700	66,700		52,900
Industrial [Member]
Summary of Segment Information
Sales										249,066	244,888		248,556
Gross profit										33,619	32,041		28,878
Selling, general, and administrative expenses										19,793	19,781		19,923
Operating income										13,826	12,260		8,955
Identifiable assets	151,157				141,506	[1]				151,157	141,506	[1]	143,827	[1]
Water Treatment [Member]
Summary of Segment Information
Sales										114,957	103,375		101,831
Gross profit										32,172	29,559		28,058
Selling, general, and administrative expenses										15,582	13,729		11,683
Operating income										16,590	15,830		16,375
Identifiable assets	$ 42,860				$ 29,001	[1]				$ 42,860	$ 29,001	[1]	$ 25,448	[1]

[1] Unallocated assets, consisting primarily of cash and cash equivalents, investments and prepaid expenses, were $53.7 million at March 29, 2015, $66.7 million at March 30, 2014 and $52.9 million at March 31, 2013.