when was water filters invented

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
when was water filters invented	1.57	0.3	1809	76	31
when	1.88	0.2	2904	11	4
was	0.74	0.1	944	77	3
water	0.4	0.2	5854	47	5
filters	1.63	0.2	7106	64	7
invented	0.13	0.9	803	42	8

Keyword	CPC	PCC	Volume	Score
when was water filters invented	1.15	0.8	9266	64
when were water filters invented	0.35	0.8	7978	86
who made water filters	1.24	0.7	6384	55
who invented water filtration	0.01	0.8	1778	35
history of water filtration	0.18	0.8	9712	27
when was the water purifier invented	0.71	1	341	14
why did nasa invent water filters	1.32	0.4	7925	71
first water filtration system	1.34	0.4	5628	79
japanese water filtration history	0.28	0.6	7526	63
nasa water filter invention	1.43	0.8	418	69
when were photo filters invented	0.98	0.7	6351	14
who invented the oil filter	1.29	0.6	7593	14
how old is the water filtration process	0.83	0.5	3153	42
facts about water filters	1.33	0.8	3947	100
when were filter cigarettes invented	1.25	0.8	4228	47
first need water filter	0.87	0.2	8069	79
water filter built in	0.11	0.2	1481	49