市面上有一種筆叫做水質檢測筆，商家宣稱將其放在靜置的水中進行檢測，就能憑借其顯示的數值判斷水質的好壞，真相到底(di)是(shi)如何(he)呢？今(jin)天，我們就來一探究竟！

水(shui)(shui)質測(ce)試筆，就是(shi)溶(rong)(rong)解(jie)性(xing)(xing)(xing)總(zong)(zong)(zong)固(gu)(gu)體(ti)(ti)(ti)測(ce)定(ding)(TDS)計，只是(shi)測(ce)定(ding)水(shui)(shui)中的(de)溶(rong)(rong)解(jie)性(xing)(xing)(xing)總(zong)(zong)(zong)固(gu)(gu)體(ti)(ti)(ti)。溶(rong)(rong)解(jie)性(xing)(xing)(xing)總(zong)(zong)(zong)固(gu)(gu)體(ti)(ti)(ti)（Total dissolved solids，縮寫TDS），又稱溶(rong)(rong)解(jie)性(xing)(xing)(xing)固(gu)(gu)體(ti)(ti)(ti)總(zong)(zong)(zong)量(liang)，測(ce)量(liang)單位(wei)為毫(hao)克/升(sheng)（mg/L）,它表明(ming)(ming)1升(sheng)水(shui)(shui)中溶(rong)(rong)有(you)多少毫(hao)克溶(rong)(rong)解(jie)性(xing)(xing)(xing)固(gu)(gu)體(ti)(ti)(ti)。TDS測(ce)試筆是(shi)通過筆端(duan)的(de)兩個電極(ji)測(ce)試水(shui)(shui)的(de)導電性(xing)(xing)(xing)，導電性(xing)(xing)(xing)越好，TDS值越高，說明(ming)(ming)水(shui)(shui)中溶(rong)(rong)解(jie)性(xing)(xing)(xing)總(zong)(zong)(zong)固(gu)(gu)體(ti)(ti)(ti)含量(liang)越高。在自(zi)來水(shui)(shui)中，溶(rong)(rong)解(jie)性(xing)(xing)(xing)總(zong)(zong)(zong)固(gu)(gu)體(ti)(ti)(ti)主要指無機鹽，包括人體(ti)(ti)(ti)所需的(de)鈣(gai)、鎂、鈉、鉀(jia)等(deng)礦物質。國(guo)家飲用水(shui)(shui)衛生標準為：溶(rong)(rong)解(jie)性(xing)(xing)(xing)總(zong)(zong)(zong)固(gu)(gu)體(ti)(ti)(ti)≤1000mg/L，而南海區一(yi)般在120mg/L左右，符(fu)合國(guo)家生活飲用水(shui)(shui)衛生標準。

其(qi)實(shi)，我們(men)僅靠溶解性總固體含量高低判(pan)斷自來水(shui)是否安全健康是不科學的。測(ce)量水(shui)質好(hao)壞(huai)的指(zhi)標足(zu)有106項之多，而(er)TDS也(ye)只是眾(zhong)多指(zhi)標之一(yi)。合格的飲用水(shui)必須滿(man)足(zu)：濁度(du)、菌(jun)落(luo)總數(shu)、微生物數(shu)、重(zhong)金屬(shu)濃(nong)度(du)及有機物含量等綜(zong)合指(zhi)標的標準。央視的一(yi)檔節目曾(ceng)測(ce)試過(guo)TDS檢(jian)(jian)(jian)測(ce)筆(bi)，在(zai)實(shi)驗中(zhong)(zhong)節目組用TDS檢(jian)(jian)(jian)測(ce)筆(bi)檢(jian)(jian)(jian)測(ce)出純凈水(shui)的數(shu)值(zhi)為1，而(er)往(wang)純凈水(shui)中(zhong)(zhong)滴入(ru)10萬個大腸(chang)(chang)桿菌(jun)時，數(shu)值(zhi)顯(xian)示(shi)3，滴入(ru)50萬個大腸(chang)(chang)桿菌(jun)時，數(shu)值(zhi)顯(xian)示(shi)7，而(er)按照商家(jia)給的對比表，仍在(zai)理(li)想(xiang)飲用水(shui)范圍之內。可見，檢(jian)(jian)(jian)測(ce)筆(bi)并沒有檢(jian)(jian)(jian)測(ce)出水(shui)中(zhong)(zhong)致(zhi)病菌(jun)的含量，所謂的水(shui)質檢(jian)(jian)(jian)測(ce)筆(bi)也(ye)并不能檢(jian)(jian)(jian)測(ce)出水(shui)質的好(hao)壞(huai)。

水質檢測筆（TDS計）只能檢測水中的無機鹽含量這一項指標，所以不能用其檢測數據來衡量和評價飲用水的水質。因為飲用水水質的檢測和評價還有很多指標，既包括反映水質狀(zhuang)況的綜(zong)合指標，如(ru)溫度(du)、色度(du)、濁度(du)、pH值、余氯、氨(an)氮(dan)、總磷、總氮(dan)、化(hua)學(xue)需氧(yang)量等等，還包(bao)括微生(sheng)物(wu)、有機物(wu)、重金屬等有毒物(wu)質，如(ru)酚類、氰(qing)化(hua)物(wu)、砷、鉛(qian)、鉻、鎘、汞和(he)有機農(nong)藥等等。