使用蓝色洁厕块有供水系统的限制吗？

管线的事儿等专业人士来回答了，先来说一下后半部分。

看起来这里面的叙述是吧矛头指向洁厕块了，那我们就先看看洁厕块里面有什么成分。

因为大概是没有要求标注的原因，很多洁厕块产品上并没有详细的成分表，比如我家的只写到“表面活性剂”这种程度。查到一些资料，大体上说其中起到主要作用的应该还是阴离子表面活性剂，比如烷基磺酸盐（这里说到阴离子表面活性剂占15~30%）。当然其他还有不少辅料，根据这里说，这种块块的骨架是硬脂酸钠和石蜡配合制成的，其中还加入了作为粘结剂的糊精和聚乙烯醇，以及脂肪醇聚氧乙烯醚。其他的也可能含有杀菌剂等，第一个链接里提到的产品加了邻苯基苯酚钠（Sodium O-Phenylphenate）。

生活污水进入饮用水中肯定是会带来污染的，但像上面提到的表面活性剂和辅料成分其实毒性都比较小，也没有发现致癌。关于烷基磺酸盐可能疑虑比较多一些，不过在既往的研究中也并未发现致癌的迹象。

SDS is not carcinogenic when either applied directly to skin or consumed.[20] A review of the scientific literature stated "SLS [SDS] was negative in an Ames(bacterial mutation) test, a gene mutation and sister chromatid exchange test in mammalian cells, as well as in an in vivo micronucleus assay in mice. The negative results from in vitro and in vivo studies indicate SDS does not interact with DNA."[21] The same review also stated "In the only carcinogenicity study available, SDS was not carcinogenic in Beagle dogs, though the short study duration and limited details provided limit the significance that can be attached to the data."

它对人主要的不好还是体现在刺激性、让皮肤过度干燥等等，而且这方面也是直接接触洗涤剂时会比较突出。

邻苯基苯酚钠的毒性也不高，只有在高剂量的动物实验当中发现过有限的致癌性。

Human health effects from OPP at low environmental doses or at biomonitored levels from low environmental exposures are unknown. OPP is considered to be moderately toxic after acute oral doses in animal studies. Chronic dosing in animals resulted in systemic effects such as weight loss and anemia, but no neurologic, reproductive, or developmental toxicity (Bomhard et al., 2002; U.S.EPA 2006). OPP was not mutagenic. Dermally-applied OPP was notcarcinogenic in a 2-year experimental in animals (NTP, 1986). In high dose animal studies, OPP or SOPP produced carcinomas of the bladder only after phase II detoxification pathways were saturated, leading to production of two metabolites, ortho-phenylhydroquinone or ortho-phenylbenzoquinone. These metabolites may induce carcinogenicity via nongenotoxic regenerative hyperplasia of the bladder (Appel, 2000; Bomhard et al., 2002; Brusick, 2005; Kwok et al., 1999; Nakagawa et al., 1992; Smith et al., 1998; U.S.EPA 2006), or, less likely, by possible genotoxic mechanisms (Hagiwara et al., 1984; Ito et al., 1984; Murata et al., 1999; Pathak and Roy, 1993; Zhao et al., 2002). IARC has classified SOPP as a possible human carcinogen and OPP as not classifiable as a human carcinogen. Additional information is available from U.S.EPA at: http://www.epa.gov/pesticides/

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从这些信息来看，“强致癌”感觉还是没什么道理的。

这里还有一个洁厕块的SAFETY DATA SHEET，提到的需要警惕的主要是吸入、皮肤和眼部接触，列出的主要需要警惕的物质也就是烷基磺酸盐。