Defendants were convicted of various and sundry counts relating to the illicit manufacture of methamphetamine. They appeal from the denial of their pretrial motions to suppress evidence found at their residences, contending insufficiency of the affidavit offered to obtain the search warrants. , We affirm.

I. BACKGROUND

Lee Norman Clark is a physician. Fred Landis is a dentist. They, along with Carolyn Landis, were convicted of manufacturing methamphetamine, conspiracy and attempt to manufacture methamphetamine, and possession of the controlled “precursor chemical” phenyl-2-propanone (P2P) with intent to manufacture methamphetamine. Most, if not all, of the dispositive evidence against Clark and the Landises was obtained through searches of their respective residences. Warrants for those searches were issued by Senior U.S. District Judge Sherrill Halbert, on the basis of identical affidavits executed by DEA Special Agent Patrick Gregory.

This case presents the essentially factual question of whether probable cause existed to justify the search of the Clark and Lan-dis residences, using the standards recently set forth in Illinois v. Gates,-U.S.-, 103 S.Ct. 2317 , 76 L.Ed.2d 527 (1983). When, as here, confidential informants are used to supply facts necessary to a determination of probable cause, the two-pronged Aguilar-Spinelli test generally has been applied. First, the affidavit had to reveal adequately the informant’s basis of knowledge — that is, how the informant came upon the information given. Second, the affidavit had to establish the veracity of the informant or the reliability of that particular report, as by a history of reliable information or by corroboration. 103 S.Ct. at 2327 & n. 4. In Gates, the Supreme Court abandoned the two-pronged test, saying instead that veracity, reliability, and basis of knowledge are all relevant but are not separate and independent requirements. Id. 103 S.Ct. at 2327-28 . As the Court stated:

Id. 103 S.Ct. at 2332 (citation omitted). -We now turn to the individual defendants.

II. LEE NORMAN CLARK

Most of the inculpatory information about Lee Clark’s activities comes from one informant, referred to herein as Source # 1. Source # 1 told DEA agents that Lee Norman Clark was a medical doctor who did not work but who derived his income from selling “speed.” Farrell Clark, Lee’s son, had given him this information. Source # 1 apparently had been inside the Clark residence, for he had observed several strange chemicals in Lee Clark’s bedroom. Source # 1 was told by Leah and Farrell Clark that Lee was manufacturing methamphetamine in his basement, and Source *542 # 1 apparently had seen the basement, describing it as a vented room. Further, Lee Clark himself had approached Source # 1 about the possibility of selling drugs for him.

Apparently, the basis of Source # l’s knowledge is observation of the methamphetamine laboratory and the personal trust of Lee Clark himself. It is hard to imagine a more reliable basis for information than one who had been taken into the defendant’s confidence. As to the veracity of the informant, a police investigation corroborated much of his information. Clark was in fact a medical doctor, but apparently did not practice. His listed place of business was his home, at which there was no visible evidence of a medical practice. Clark did not have a listed telephone number or hospital privileges and the only prescriptions he wrote for controlled substances were for members of his family. Finally, Lee Clark’s phone tolls in the first six months of 1982 showed calls to chemical suppliers but the chemicals were apparently unrelated to medical practice, since Lee Clark was not practicing. In sum, Source # l’s information would have been an acceptable basis for a probable cause determination even under Aguilar and Spinelli. Under current law, the search of the Clark residence must be upheld.

Clark, however, contends that Source # l’s information was stale. See Sgro v. United States, 287 U.S. 206 , 53 S.Ct. 138 , 77 L.Ed. 260 (1932); United States v. Freeman, 685 F.2d 942, 951 (5th Cir.1982). The facts point to a different conclusion. Much of the corroborative information was learned on or around April 1982, two months before the warrant issued. Because Source # 1 learned his information in late 1981 and the information was corroborated in April 1982, Judge Halbert had a substantial basis for concluding that the Clark residence housed illegal activity of a continuous nature. The continuous nature of the activity diminishes the significance of the time lag between the acts described in the affidavit and presentation of the affidavit to the magistrate. United States v. Hershe-now, 680 F.2d 847, 853 (1st Cir.1982); Mapp v. Warden, New York State Correctional Institution for Women, 531 F.2d 1167 ,1171— 72 (2d Cir.), cert, denied, 429 U.S. 982 , 97 S.Ct. 498 , 50 L.Ed.2d 592 (1976); United States v. Johnson, 461 F.2d 285, 287 (10th Cir.1972). Judge Halbert thus had a substantial basis for finding probable cause that contraband or evidence of crime would be found in the Clark residence in June 1982.

III. FRED AND CAROLYN LANDIS

The search of the Landis residence presents a much closer question. The portions of Special Agent Gregory’s affidavit that pertain to the Landis residence relate the following facts:

The only explicit association between the Landis residence and the criminal manufacture of methamphetamine was provided by Source # 3. To credit a confidential source’s information in making a probable cause determination, the affidavit should support an inference that the source was trustworthy and that the source’s accusation of criminal activity was made on the basis of information obtained in a reliable way. United States v. Pryba, 502 F.2d 391, 402 (D.C.Cir.1974), cert, denied, 419 U.S. 1127 , 95 S.Ct. 815 , 42 L.Ed.2d 828 (1975); see Satchell v. Cardwell, 653 F.2d 408, 411 (9th Cir.1981), cert, denied, 454 U.S. 1154 , 102 S.Ct. 1026 , 71 L.Ed.2d 311 (1982). We think the facts in the affidavit, taken as a whole, did provide a substantial basis for Judge Halbert to credit Source # 3’s information and conclude that criminal activity probably was taking place.

First, Source # 3’s information was reliable in the past and her current information was .based on her personal observation of distinctive glassware. Those facts lend credibility to a confidential source. See United States v. Moore, 522 F.2d 1068, 1073 (9th Cir.1975), cert, denied, 423 U.S. 1049 , 96 S.Ct. 775 , 46 L.Ed.2d 637 (1976).

Second, her information was corroborated to a significant degree by the agents’ investigation. Source # 3 said that Lee Norman Clark would be at the Landis residence; not one but two of his vehicles were identified there. Furthermore, Agent Gregory heard distinctive sounds coming from an outbuilding on the property. Although Agent Gregory likened the sounds to those of a pump and running water, which at first blush sounds innocuous enough, a DEA agent’s “special training and experience may enable him reasonably to suspect that criminal activity is afoot from observing what might appear innocuous to the uninitiated.” United States v. Woods, 720 F.2d 1022, 1027 (9th Cir.1983).

Our conclusion here is not inconsistent with United States v. Tate, 694 F.2d 1217 (9th Cir.1982), petition for cert, filed, 52 U.S.L.W. 3011 (U.S. July 8, 1983) (No. 83-24). In Tate, an informant smelled a strong odor of ether emanating from the defendants’ premises. Officers corroborated the informant’s observation and told the magistrate that the manufacture of phencyclidine (PCP) emits a strong odor of ether. We held that the smell of a substance having many innocuous uses, without more, does not establish probable cause to search. Id. at 1220-21. Here, however, the sounds like that of a pump and running water did not stand alone. The informant stated that methamphetamine manufacture was taking place — a factor conspicuously absent in Tate, id. at 1221 — and the DEA agent’s observations corroborated that information.

Finally, Lee Clark’s presence at the Lan-dis residence with glassware used in a chemical manufacturing operation, combined with the overwhelming indications provided by Source # 1 that Lee Clark was a methamphetamine manufacturer, further buttressed Source # 3’s conclusion that methamphetamine was being manufactured at the Landis residence. Interlocking tips from different confidential informants enhance the credibility of each. United States v. Weinrich, 586 F.2d 481, 490 (5th Cir.1978), cert, denied, 441 U.S. 927 , 99 S.Ct. 2041 , 60 L.Ed.2d 402 (1979); United States v. Hyde, 574 F.2d 856, 863-64 (5th Cir.1978); see Jones v. United States, 362 U.S. 257, 271 , 80 S.Ct. 725, 736 , 4 L.Ed.2d 697 (1960), overruled on other grounds, United States v. Salvucci, 448 U.S. 83 , 100 S.Ct. 2547 , 65 L.Ed.2d 619 (1980); United States v. Frei-tas, 716 F.2d 1216, 1222 (9th Cir.1983).

Thus, when confronted with the affidavit in this case we cannot say that there was no *544 substantial basis for Judge Halbert to believe Source # 3 and thereby find a “probability, and not a prima facie showing, of criminal activity [which] is the standard of probable cause.” Spinelli v. United States, 393 U.S. 410, 419 , 89 S.Ct. 584, 590 , 21 L.Ed.2d 637 (1969).

The judgments of conviction appealed from are AFFIRMED.

. By a toss of the coin, Source # 1 is referred to here as “he” and Source # 3 as “she.”