盡(jin)管農(nong)業、畜(chu)牧業生產(chan)產(chan)生了嚴重的面源污染，但是(shi)城(cheng)市(shi)廢污水所造(zao)成(cheng)的點(dian)源污染仍是(shi)對(dui)水環境造(zao)成(cheng)破壞的主要因(yin)素(su)。如果解決的不好(hao)，隨著城(cheng)市(shi)化進程和第二、第三(san)產(chan)業的發(fa)展，城(cheng)市(shi)用水量的增加，城(cheng)市(shi)廢污水會對(dui)水環境造(zao)成(cheng)更大的破壞。目前(qian)城(cheng)市(shi)污水處(chu)理(li)率大約是(shi)30%，許多城(cheng)市(shi)至今(jin)還沒(mei)有(you)污水處(chu)理(li)廠，而且很多污水處(chu)理(li)廠沒(mei)有(you)真正有(you)效(xiao)行，大量的城(cheng)市(shi)污水未經(jing)處(chu)理(li)直接排入水體(ti)。

在(zai)我國(guo)(guo)(guo)(guo)，“土渠輸水、大水漫灌(guan)”的農業(ye)(ye)灌(guan)溉(gai)方(fang)式還仍在(zai)普遍(bian)沿用(yong)(yong)，灌(guan)溉(gai)用(yong)(yong)水一半在(zai)輸水中就滲漏損失了，灌(guan)溉(gai)用(yong)(yong)水的利用(yong)(yong)系數大多(duo)只(zhi)有(you)0.4，不足一些發(fa)達(da)國(guo)(guo)(guo)(guo)家(jia)(jia)的一半水平(ping)(ping)。我國(guo)(guo)(guo)(guo)每平(ping)(ping)方(fang)水灌(guan)溉(gai)后(hou)增產糧(liang)食0.5公(gong)(gong)斤(jin)(jin)，發(fa)達(da)國(guo)(guo)(guo)(guo)家(jia)(jia)則可(ke)達(da)2公(gong)(gong)斤(jin)(jin)。工(gong)業(ye)(ye)，因為(wei)現有(you)用(yong)(yong)水設(she)施(shi)技術落(luo)后(hou)，我國(guo)(guo)(guo)(guo)工(gong)業(ye)(ye)萬元產值(zhi)用(yong)(yong)水量為(wei)103立方(fang)米(mi)，美國(guo)(guo)(guo)(guo)是8立方(fang)米(mi)，日本只(zhi)有(you)6立方(fang)米(mi)，取用(yong)(yong)水審計(ji)，是發(fa)達(da)國(guo)(guo)(guo)(guo)家(jia)(jia)的10～20倍；我國(guo)(guo)(guo)(guo)工(gong)業(ye)(ye)用(yong)(yong)水的重(zhong)復利用(yong)(yong)率僅為(wei)40%左右，而(er)發(fa)達(da)國(guo)(guo)(guo)(guo)家(jia)(jia)平(ping)(ping)均為(wei)75%～85%。

人(ren)(ren)均(jun)(jun)用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)：人(ren)(ren)均(jun)(jun)用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)在數值于一定的(de)計量(liang)(liang)時(shi)間(年(nian))內城(cheng)(cheng)(cheng)(cheng)市(shi)中每個居民的(de)平(ping)均(jun)(jun)綜(zong)(zong)合用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)，此處“綜(zong)(zong)合用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)”指(zhi)各種用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)之(zhi)和，即包括工業(ye)用(yong)水(shui)(shui)(shui)(shui)、城(cheng)(cheng)(cheng)(cheng)市(shi)居民住宅用(yong)水(shui)(shui)(shui)(shui)、公共建筑(zhu)用(yong)水(shui)(shui)(shui)(shui)、市(shi)政(zheng)用(yong)水(shui)(shui)(shui)(shui)、環境景(jing)觀與娛樂用(yong)水(shui)(shui)(shui)(shui)、供熱用(yong)水(shui)(shui)(shui)(shui)及消(xiao)防用(yong)水(shui)(shui)(shui)(shui)等。因此，城(cheng)(cheng)(cheng)(cheng)市(shi)的(de)人(ren)(ren)均(jun)(jun)用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)與城(cheng)(cheng)(cheng)(cheng)市(shi)的(de)性質、規(gui)模(mo)、城(cheng)(cheng)(cheng)(cheng)市(shi)化程度、工業(ye)結構布局(ju)、水(shui)(shui)(shui)(shui)資源豐缺狀況(kuang)、地理位置、水(shui)(shui)(shui)(shui)文、氣(qi)象(xiang)等有(you)關，同(tong)時(shi)也充分說明(ming)人(ren)(ren)均(jun)(jun)用(yong)水(shui)(shui)(shui)(shui)量(liang)(liang)可以(yi)作為城(cheng)(cheng)(cheng)(cheng)市(shi)節水(shui)(shui)(shui)(shui)用(yong)水(shui)(shui)(shui)(shui)的(de)綜(zong)(zong)合指(zhi)標。目前，在國內外進(jin)行城(cheng)(cheng)(cheng)(cheng)市(shi)節約(yue)用(yong)水(shui)(shui)(shui)(shui)水(shui)(shui)(shui)(shui)平(ping)評判、城(cheng)(cheng)(cheng)(cheng)市(shi)需水(shui)(shui)(shui)(shui)量(liang)(liang)預測、城(cheng)(cheng)(cheng)(cheng)市(shi)節水(shui)(shui)(shui)(shui)發展規(gui)劃編制(zhi)中均(jun)(jun)有(you)較(jiao)多的(de)應用(yong)。