Since　the　advent　of　photocatalytic　degradation　technology,　it　has　brought　new　vitality　to　the　environmental　governance　and　the　response　to　the　energy　crisis.　Photocatalysts　harvest　optical　energy　to　drive　chemical　reactions,　which　means　people　can　use　solar　energy　to　complete　some　resource-consuming　activities　by　photocatalysts,　such　as　environmental　governance.　In　recent　years,　researchers　have　tried　to　combine　photocatalyst　TiO2　with　building　materials　to　purify　urban　air　and　obtained　good　results.　One　of　the　important　functions　of　photocatalysts　is　to　degrade　organic　pollutants　in　water　through　light　energy,　but　this　technology　has　not　been　reported　in　the　practical　application　areas.　To　extend　this　technology　to　practical　application　areas,　photocatalytic　concrete　for　degrading　pollutants　in　waters　was　proposed　and　demonstrated　for　the　first　time　in　this　paper.　The　photocatalytic　concrete　proposed　based　on　the　K-g-C3N4　shows　a　strong　ability　to　degrade　the　organic　dyes.　According　to　the　experiment　results,　the　angle　of　light　source　plays　an　important　role　in　the　process　of　photocatalytic　degradation,　while　waters　with　pH　value　of　6.5–8.5　hardly　influenced　the　degradation　of　organic　dyes.　When　the　angle　of　light　source　is　advantageous　for　photocatalytic　concrete　to　absorb　more　visible　light,　more　organic　dyes　will　be　degraded　by　photocatalytic　concrete.　The　degradation　rate　of　methylene　blue　could　reach　about　80%　in　½　hour　under　desirable　conditions　and　is　satisfied　compared　with　that　of　reported　works.　This　study　implicates　that　photocatalytic　concrete　can　effectively　degrade　organic　dyes　in　water.　The　influences　of　changes　in　the　water　environment　hardly　affect　the　degradation　of　organic　pollutants,　which　means　photocatalytic　concrete　can　be　widely　used　in　green　infrastructures　to　achieve　urban　sewage　treatment.　©　2021,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.